What's your BMI?

Body mass index (BMI) is a good way to check if you're a healthy weight. Use our healthy weight calculator to find out your BMI, and get helpful information and advice.

Check your BMI or that of your child or other family members using our BMI healthy weight calculator. This tool can be used for adults and children aged two or above. Once it has calculated your BMI, it will direct you to relevant content on NHS Choices.

For adults, BMI is a measure of whether you're a healthy weight for your height.

For children aged two and over, BMI centile is used. This is a measure of whether the child is a healthy weight for their height, age and sex.

If you have a BMI above the healthy range you are at raised risk of the serious health problems linked to being overweight, such as type 2 diabetes, heart disease and certain cancers. In children, BMI centile indicates whether the child is a healthy weight.

You can go straight to information on:

Who can use BMI and BMI centile?

BMI is the best assessment of weight in adults, and BMI centile is the best assessment for children aged two and over.

Download Losing weight: Getting started, a 12-week weight loss guide combining advice on healthier eating and physical activity.

Some adults who have a lot of muscle may have a BMI above the healthy range. For example, professional rugby players can have an "obese" BMI result despite having very little body fat. However, this will not apply to most people.

BMI for adults

BMI takes into account that people come in different shapes and sizes. That's why a range of BMIs is considered healthy for an adult of any given height. 

A BMI above the healthy range indicates that you're heavier than is healthy for your height.

The ranges below only apply to adults. BMI results are interpreted differently for children.

  • BMI below 18.5: a score this low means that you may be underweight. There are a number of possible reasons for this. Your GP can help you find out more, and achieve a healthy weight.You can learn more by reading Nutrition for underweight adults.
  • BMI between 18.5-24.9: this is a healthy range. It shows that you're a healthy weight for your height. However, it's still important to eat a healthy, balanced diet and include physical activity in your daily life if you want to maintain a healthy weight.
  • BMI score of 25 or more: your BMI is above the ideal range and this score means you may be overweight. This means that you're heavier than is healthy for someone of your height. Excess weight can put you at increased risk of heart disease, stroke and type 2 diabetes. It’s time to take action. See the section below for the next step, and learn more in our Lose weight section. 
  • BMI of 30 or more: a BMI above 30 is classified as obese. Being obese puts you at a raised risk of health problems such as heart disease, stroke and type 2 diabetes. Losing weight will bring significant health improvements, and your GP can help. See the section below and learn more in Lose weight

Ethnicity, BMI and diabetes risk

New BMI advice was issued in July 2013 by the National Institute for Health and Care Excellence (NICE) to south Asian and Chinese adults, who have a higher risk of developing type 2 diabetes than white populations. These groups are advised to maintain a BMI lower than the standard 25.

The advice is: 

  • BMI of 23: Asians with a BMI score of 23 or more are at increased risk of developing type 2 diabetes. 
  • BMI of 27.5: Asians with a BMI of 27.5 or more are at high risk of developing type 2 diabetes. 

Although the evidence is less clear-cut, black people and other minority groups are also advised to maintain a BMI below 25 to reduce their risk of type 2 diabetes.

If you're overweight

If your BMI shows that you're overweight or obese it's time to take action. There’s lots of information, advice and support on NHS Choices that can help you.

  • Lose weight has information and advice on achieving a healthy weight
  • Food and diet contains information and advice on healthy eating
  • Health and fitness is full of fun and practical ideas to help you get into shape

Your GP or practice nurse can also offer advice on lifestyle changes, and may refer you to a weight loss group or discuss other treatments. Find out more in How your GP can help.

They may also measure your waist circumference. This can provide further information on your risk of certain health conditions, such as type 2 diabetes and heart disease. You can learn more by reading Why body shape matters.

Why lose weight?

For adults who are overweight or obese, losing even a little excess weight has health benefits. You’ll lower your risk of serious health problems such as heart disease, stroke, high blood pressure and type 2 diabetes.

Weight loss can also improve back and joint pain. Most people feel better when they lose excess weight.

The key is to make small, long-lasting changes to your lifestyle. If you are overweight or obese, changing your lifestyle so that you eat fewer calories can help you to become a healthier weight. Combining these changes with increased physical activity is the best approach.

To start with, you can cut down on excess calories by swapping high-calorie meals and snacks for healthier alternatives. Read Healthy food swaps to learn more.

Physical activity is an important part of losing weight, as long as it is combined with eating fewer calories. The amount of physical activity that is recommended depends on your age. Adults aged between 19 and 64 should get at least 150 minutes of moderate-intensity aerobic physical activity – such as fast walking or cycling – a week. Adults who are overweight are likely to need to do more than this to lose weight. If it's been a while since you've done any activity you should aim to build up to this recommendation gradually. Find out more in Benefits of exercise.

For more ideas on how to get you and your family active, visit Change4Life.

Height and weight chart

You can also use the height and weight chart to check if you're a healthy weight for your height. The chart is only suitable for adult men and women.

BMfor children

BMI results are interpreted differently for children.

When interpreting BMI for a child, health professionals look at a child's weight in relation to their height, age and sex. The result is called the child’s BMI centile. BMI centile is a good way of telling whether a child is a healthy weight, and is used by healthcare professionals.

Using your child’s BMI centile, a healthcare professional can tell whether they're growing as expected. You may have done something similar when your child was a baby, using the growth charts in the Personal Child Health Record ("red book").

Once your child’s BMI centile has been calculated, they will be in one of four categories:

  • underweight: below 2nd BMI centile
  • healthy weight: between the 2nd and 90th BMI centile
  • overweight: between 91st and to 97th BMI centile
  • obese: at or above 98th BMI centile. This BMI centile category is called "very overweight" in letters that are sent by the National Child Measurement Programme.

Most children should fall in the healthy weight range. A BMI at or above the 91st centile is likely to indicate your child has an increased risk of obesity-related health problems.

Some medical conditions or treatments may mean that BMI centile is not the best way to measure whether your child is a healthy weight. Your GP or other health professional can discuss this with you.

If your child is overweight

Research shows that children who are overweight or obese have a higher risk of ill health during childhood and in later life. If your child is overweight, it’s time to take action.

A GP or practice nurse can give advice and support on helping your child achieve a healthy weight as they grow. Find out more in When your child is overweight.

Page last reviewed: 07/03/2014

Next review due: 07/03/2016


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The 49 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Curtis frustrated said on 18 September 2015

BMI is a bad way to check if you are overweight. BMI was devised by a statisician not a medic. It was devised for mass calculations of populations and was not devised to check for healthy weight of any one person and relies on averages. The selection of 18.5 to 25 as a healthy BMI is not scientifically relevant. BMI 27 was previously used for the upper level of healthy. The numbers are a value judgement only. It is not used for children because it is rubbish for younger people and in fact it is irregular for most 18-21 year olds. It is also mathematically biased for very tall and very short people.
Squaring the height in the calculation is to make the figures easy to compute the true figure should be less for men in particular. Refuse BMI calculations and insist on bady fat as the reliable measure of healthy weight.

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Absolutely frozen said on 18 July 2015

To make it easy to measure, if you think you are obese, make sure your waist measurement is half your height. Body builders using the BMI appear to be obese using that way if measuring when in fact they have very little fat.

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Ironia said on 03 March 2015

A major problem with BMI is that it does not take into account that people come in light, medium, and heavy, bone structures, and that everyone loses muscle mass and bone density as they age. Apparently age 25 is the peak: why dancers and athletes have short careers.

It is thus merely a rough guide, but one has NHS sites and real live doctors telling one one is 'underweight', because of an algorithm. If you are 16 or 60 and a good slim healthy weight the site advises you to find out how to put on weight!

Get a more suble algorithm is my suggestion; in the meantime, doctors and nurses use your eyes.

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Karactus said on 02 February 2015

I from mixed ethnic background of white and asian. Should I class myself as Asian or White for the BMI test? My BMI is 24.5 so I am okay if I class myself as white but not okay if I class myself as Asian. If I am still to be classed as Asian then what about my children who are only 25% Asian ? When are we no longer Asians for BMI results? How asian do we need to be? Where does Asian start ?

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emicattt said on 14 August 2013

If I use my real birthday (17y10m28d) it tells me I'm 5th centile and healthy. However, if I tell it my 18th birthday is today it tells me I'm 17.61 and underweight. On the spectrum it's yellow and very close to red. Do one month and three days really make that much difference? Am I healthy or underweight?

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asdasdasdasd said on 03 October 2012

BMI index is old. Successor index is an ABSI, that is more accurate. Try it at http://www.absi-calculator.com

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User363614 said on 24 December 2011

Is it true that people with a BMI of a little over 25 have better life expectancy and health than people in the 'normal' range?

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cazza0310 said on 16 June 2011

My BMI says I'm obese and that's probably because I am !!!

I can't blame the reading on the calculator, I can't say it is a load of rubbish because it doesn't take into consideration x, y and z......

I can say, I'm overweight and that isn't dependant on whether I go by the scales/bmi or how tight my jeans are!!! Using every method of calculation - I'm still obese!!!

Why do people have to be so negative? No calculator is going to be able to take into consideration every variable.

Beefing that BMI says a rugby player is overweight is like saying the scales are unfair because he weighs alot even though he is fit??? Its muscle and it weighs more than fat, your not going to try to lose weight because the scales say you weigh more than someone the same height/size who doesn't excercise - you will just accept it for what it is, so why is BMI any different?

You know if you are overweight, just like you know to ignore BMI when you get to the stage where you are so fit it effects your fat to muscle ratio.....(you already do this with your scales!)

BMI figures may not suit everybodies taste, however for others, it can be something to aim for rather than just monitoring the lbs.

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Camels Toe said on 12 May 2011

BMI is rubbish. According to BMI many rugby players would be overweight. Muscled people would be too heavy. I am more muscled than average for a female - I do weight training and have bigger than usual shoulders and muscled legs. I am 9stone 6 and some charts say I am overweight and should be 9st 2 or lower yet I am a size 8-10 because I have the fat in the right places (not around the middle). If I lose any more weight my face will get really thin and I will lose energy and performance. Waist to hip ratio is a better way of telling. Fat should be evenly distributed and not held on the stomach.

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ashtonmarc said on 06 April 2011

BMI is a nonsense. It's far to simpistic and doesn't make any allowance for fitness,muscle mass and general build.

I'm 6'2 and 16 stone. Using the BMI scale Im apparently over weight and just under obese! yet i run 35 miles a week, can run 5 miles in 36 minutes ,10hrs of strength training and cycle 100 miles a week . Using the BMI Im in bad shape and need to lose weight urgently!

Forget BMI-Just stand in front of a mirror naked and be honest with yourself, IMO a far more accurate guide to the shape your in.

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portiapoppy1 said on 20 January 2011

I'm soo sick of hearing people complain about the NHS. In most countries you have to pay to have health care of any sort. If you're so worried about your BMI go get it checked at the doctors. On the NHS, of course.

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TEAMHVA said on 07 January 2011

I don't need a calculator to tell me I am over weight I just need good practical advice on how to loose it. We obsess so much about it and I feel it can be a hinderance because people don't use it correctly.

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gymer said on 04 January 2011

Im 5ft9 and a UK size 6 but my BMI is 22 (the hight side of normal)...
hmmm... maybe we shouldnt go by BMI if we do cardio and weights 6 times a week?

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whittakeramy said on 15 December 2010

I think there should be a different system as BMI will be worked out using your hight and weight and so you could have someone who is 14st and 5ft 7 and they would be obese but how would they know that this person is not a muscular person, there can be a lot of difference in health of 2 people who, on paper, are the same heigh and weight. Fat percentile should be taken into concideration.

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mc1395 said on 19 September 2010

I dont understand how this works propperly because my reading comes off at probably overweight yet i play basketball for england and train 7 times a week at a high intensity so im not unfit and i also eat a helathy balanced diet so how am i not a healthy weight?.

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NormalWoman said on 26 July 2010

I am 11st 3lbs, 5ft 6, pear shaped and a size 12-14. Altough with the erratic sizes on the high street nowadays I like to say my clothes size is whatever fits right, but mostly is a 12-14.
I have lost quite a bit of weight. At Xmas last year I was 12st 10lbs. The lowest weight I have ever been is 10st 4lbs, I looked very thin, my rib cage poked out, even above my chest, and was fainting regularly through not eating properly. All in the aim to look like something that I am not.
Now, I am just aiming to be a healthy weight for me despite but BMI calculator says - which at the moment puts me at just overweight. When I get to 11st I will be considered healthy - but only just. But I think its how you feel that counts. And good mental health is probably even more important than being a 'healthy' weight within BMI standards.
I am one of these people that has always been heavier on the scales. But thats just me, and I have grown tired of being ashamed of it.
If you have small shoulders, are naturally petitie in height and build you will be nice and light. If you are slightly taller, a bit broader etc, you should be further up the scales. All relative to YOUR build. And everyone is different.
Some people who are larger than me in clothes size and waist and hip measurements are lighter than me. Its all down to your personal build.
For women and men, we just need to be happy in our skins and stop aspiring to be the images in the magazines. When if you look around - very few people look like that. Personally, I love men with a little but of wobble on their tummy. It shows they are real, enjoy life, and are not vain. And its normal!!!
Not everyone seeks 'perfection'. We all give ourselves such hard times with how we look. Its time to stop!

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sammiefields2512 said on 25 March 2010

Interesting point

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User63450 said on 13 November 2008

there is nothing more important than hearing what we need to hear, rather than what we would like to hear.I have just been weighed and had my height measured at a pre-op appointmen. As i have been using an electric wheelchair for a year i am grateful for this help. So this is a thank you from me

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User50762 said on 09 October 2008

Just a few points....

Firstly - I really feel that people should look carefully at the BMI caclulator before whining about it not being in pounds/ounces or not knowing their height in centimeters etc - THERE IS A BUTTON TO CHANGE BETWEEN IMPERIAL AND METRIC and it took me about 10 seconds to see it.

Secondly - everyone knows that muscle weights more than fat, hense why fit and healthy rugby players would have high BMIs and why the gent that has 12% body fat, 34 inch waist and goes to the gym 4 times a week has a high BMI. You know full well that you arent over-weight so why bother checking this?

BMI is only really useful for people who are carrying a few extra pounds, people who can feel that extra wobble etc or for people who are clearly over weight to find out by how much and what they can do. There is no point in someone who is slim and goes to the gym 5 times a week checking their BMI because they are clearly not over-weight yet their BMI will be high due to muscle weighting more than fat.

Often as you tone up you don't actually lost weight because you are gaining muscle.

Just my opinions....hope it helps reduce the whining.

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Miss Khaos! said on 22 September 2008

Female: 10st 1lb, 5ft 3. BMI-25.

I'm a size 10 sometimes a size 12. I'm trim, and when people ask me how much I weigth they're usually shocked by the amount.

I do karate 3 nights a week for 2 hours each time. And water aerobics for 1 hour each week.

Surely I'm not overweight?

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User38292 said on 08 September 2008

Wow, even though I am 6' tall, 12% body fat, have a 34" waist and go to the gym 3-4 times a week, I am obese with a BMI of 36.1%!

BMI is a load of crap

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ashleigh said on 20 August 2008

surely it counts on your age?

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Daisy said on 19 August 2008

The BMI calculator is fantastic - so helpful in both measures. Happy to say that I am considered healthy.

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lorraine said on 30 July 2008

just found out my bmi is 30.48 im shocked but its what i needed to see so now im going to join slimming world. my clothes had become tight but didnt think i looked that much over weight. im 5ft 3 and wiegh 12st 6.

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seleena said on 23 July 2008


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JamesG said on 22 July 2008

The BMI should be used as a guage. This is not just to get an ideal BMI and a smug grin. Do you really need a computer to tell you if you are overweight or unfit? Use the calculator (which works very well) and work the rest out for yourself. When was the metric system introduced?? - circa 1969 - Come on catch up!
PS: after selecting your height or weight - move the mouse directly away from the chart ie to the left for height and straight down for weight. Enjoy life.

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Kath said on 21 July 2008

I know it's a bit twee, but I did like the idea of it using my name! Also, because I am obese (just by 2 points, and trying hard - honest!) it was really kind by starting off with saying "unfortunately etc. etc...."

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Loz said on 16 July 2008

It says im healthy weight but im at the higher end of healthy so im still going to try and lose weight

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Mike said on 15 July 2008

So what about "older people" How old? and can they be happy with a BMI a bit larger than "normal"; or should they be aiming for a lower than normal BMI?

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flaby75 said on 03 July 2008

fatso my b.m.i. is a shock to me i must do something as i am very short of breath and suffering athritis pain in my one good knee as i already have had a knee replacement which didnt turn out so good i cant have the other knee done as it could turn out like my other knee. MYproblem is i cant seem to feel myself getting full up.

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john said on 25 June 2008

i had to guess my weight by converting first to pounds then to kilos, wouldnt a choice of both measuring systems be more appropriate to young AND old alike, the result i got is suspect .

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Ben said on 16 June 2008

how can this thing put someone in the obese category when rugby players are shorter than me and weigh more? does that mean i have to tell all rugby players I meet who are 6 foot tall and 17 stone that they are in danger of heart disease and ill health and should change their diet, even though they train 5 times a week???!! erm... something wrong somewhere...

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random112222 said on 10 June 2008

my weight dosent bother me i am on 9stne whitch is not bad i dont worry about my height ever peple take the mick cos i am small but i dnt care

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retsil said on 03 June 2008

All you need to know is the 25 bit, anything else is about minor detail and though there shouldn't be much variation from site to site, I wouldn't lose sleep over it. At 25 BMI.....you are still in the healthy range.

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dawn_luckylady said on 03 June 2008

how come ive been to 4 different sites all for bmi and all tell me different 25.53,25.22, 25.27, and 25.2 :-(

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Graham0303 said on 31 May 2008

I was 17stone and suffering with very painful knees. Thanks to my GP who prescribed me xenical I was able to loose a good bit of weight and am now BMI 27.17 and 14stone 11lbs. I know I have a bit to go yet but the rewards have been... Lowering of BP and very little pain in the knee's. I still have about a stone to go, but I feel that my GP's help and advice has been brilliant.

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Jean said on 07 May 2008

As a 5' 4" female with a BMI of 24.84, I am near the top of the healthy range, but I am heavier than I would like (and heavier that I have been in my younger days). I read somewhere that BMI should be calculated in relation to age as well as weight and height - is this so? I am 65 and and would like to know about this. Jean.

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Anonymous said on 28 April 2008

it's say that mine is underweight..it woudn't even let me put my proper weight in cause it didnt fit into the guidelines...im confused cause im definitely not underweight :S

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mary said on 21 April 2008

Mine is 15.7 but I look fine!

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r said on 12 April 2008

i used the BMI calculator and was pleased to find I was just a little overwieght 26.12 so with some effort I will fight not to gain any more !

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karon said on 12 April 2008

i anly know my weight in stones and ounces and my height in feet and inches

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michael said on 12 April 2008

the calculator is clearly designed by someone who cares nothing about ease of use and just wants it to look pretty ... I found it impossible to enter my correct weight (11st 7) .. the numbers just kept leaping about ... is that because it's a leap year?

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ChubbyChap said on 26 March 2008

Male 53yrs old 6ft 1in tall 18st 8lbs BMI 34.11. Time to change and get rid of that 9 months pregnant shape.

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Gilly said on 24 March 2008

I am a trim size 14 - slim but with curves. I am 5ft 6 inches tall but look taller. I weigh almost 13 stones and most people dont believe me when I tell them. I lost 2 stones and looked anorexic - honestly! I think if you are fit and healthy and look fine - your bmi is a load of rubbish. My partner is an athlete - his bmi shows him to be overweight - he is far from it. Please used the bmi calculator sensibly and dont panic.

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fred said on 20 March 2008

it was very good. it helped me to understand that i am not actually overweight but health. i have more confidence now. thanks virtual man!!!!!!!!

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Anonymous said on 18 March 2008

It is the first time in my experience that I have been told that my name is necessary to calculate my BMI.


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Anonymous said on 14 March 2008

Just click on the "metric" box, and it changes to imperial.

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luke46 said on 13 March 2008

whats wrong with pounds & ounces, i to cant
understand metric.

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yvonne said on 11 March 2008

Like a lot of people, I don't know my height or weight in metric! Why not give both options. I would need to find a calculator which also does conversions.

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