BMI Calculator

Check your BMI according to your age, sex, height and weight.

BMI is a screening measure and is not a medical diagnosis. For individual health advice, consult a qualified healthcare professional.

BMI Assessment for School & College Students

For children and adolescents aged 5–19 years, BMI should be interpreted according to age and sex. There is not one fixed BMI range that applies to every boy or girl in a particular school or college age group.

Age group Typical setting Assessment
5–9 years Primary school BMI-for-age + sex
10–12 years Upper primary / middle school BMI-for-age + sex
13–15 years Secondary school BMI-for-age + sex
16–19 years Senior secondary / college BMI-for-age + sex

WHO BMI-for-age interpretation — 5 to 19 years

BMI-for-age Z-score WHO interpretation
< -3 SD Severe thinness
-3 SD to < -2 SD Thinness
-2 SD to +1 SD Not classified as thinness/overweight by these cut-offs
> +1 SD to +2 SD Overweight
> +2 SD Obesity
Important: For students aged 5–19, the numerical BMI values corresponding to these categories change with age and sex. Therefore the calculator should use the child’s exact age and sex against the WHO BMI-for-age reference rather than applying adult BMI cut-offs.
Reference: World Health Organization (WHO), BMI-for-age reference for children and adolescents 5–19 years.

Adult BMI ranges

BMI Category
Below 18.5 Underweight
18.5 – 24.9 Normal range
25 – 29.9 Overweight
30 and above Obesity
(function(){ var root = document.getElementById(“BK_BMI_TOOL”); if(!root) return; var lang = “en”; var type = “adult”; var sex = “male”; var unit = “cm”; function id(x){ return document.getElementById(x); } /* LANGUAGE */ id(“BK_EN”).onclick = function(){ lang = “en”; id(“BK_EN”).style.background = “#1a73e8”; id(“BK_EN”).style.color = “#fff”; id(“BK_HI”).style.background = “#fff”; id(“BK_HI”).style.color = “#555”; var en = root.querySelectorAll(“.BK_EN”); var hi = root.querySelectorAll(“.BK_HI”); for(var i=0;i<en.length;i++){ en[i].style.display = ""; } for(var j=0;j<hi.length;j++){ hi[j].style.display = "none"; } updateResult(); }; id("BK_HI").onclick = function(){ lang = "hi"; id("BK_HI").style.background = "#1a73e8"; id("BK_HI").style.color = "#fff"; id("BK_EN").style.background = "#fff"; id("BK_EN").style.color = "#555"; var en = root.querySelectorAll(".BK_EN"); var hi = root.querySelectorAll(".BK_HI"); for(var i=0;i<en.length;i++){ en[i].style.display = "none"; } for(var j=0;j= minAge && age <= maxAge; if(!validAge){ id("BK_AGE_ERROR").style.display = "block"; id("BK_AGE_ERROR").textContent = type === "student" ? (lang === "hi" ? "विद्यार्थी आकलन के लिए उम्र 5 से 19 वर्ष रखें।" : "For student assessment, enter an age from 5 to 19 years.") : (lang === "hi" ? "वयस्क आकलन के लिए उम्र 20 वर्ष या अधिक रखें।" : "For adult assessment, enter an age of 20 years or above."); }else{ id("BK_AGE_ERROR").style.display = "none"; } /* HEIGHT */ var validHeight = true; if(unit === "cm"){ var cm = parseFloat(id("BK_CM_INPUT").value); if(isNaN(cm) || cm 250){ validHeight = false; }else{ heightM = cm / 100; } }else{ var ft = parseFloat(id(“BK_FT_INPUT”).value) || 0; var inch = parseFloat(id(“BK_IN_INPUT”).value) || 0; if( ft 8 || inch = 12 ){ validHeight = false; }else{ heightM = ((ft * 12) + inch) * 0.0254; } } if(!validHeight){ id(“BK_HEIGHT_ERROR”).style.display = “block”; id(“BK_HEIGHT_ERROR”).textContent = lang === “hi” ? “कृपया सही लंबाई दर्ज करें।” : “Please enter a valid height.”; }else{ id(“BK_HEIGHT_ERROR”).style.display = “none”; } /* WEIGHT */ var validWeight = !isNaN(weight) && weight > 2 && weight < 400; if(!validWeight){ id("BK_WEIGHT_ERROR").style.display = "block"; id("BK_WEIGHT_ERROR").textContent = lang === "hi" ? "कृपया सही वज़न दर्ज करें।" : "Please enter a valid weight."; }else{ id("BK_WEIGHT_ERROR").style.display = "none"; } if( !validAge || !validHeight || !validWeight ){ id("BK_RESULT").style.display = "none"; return; } var bmi = weight / (heightM * heightM); id("BK_VALUE").textContent = bmi.toFixed(1); /* ====================================================== ADULT BMI ====================================================== */ if(type === "adult"){ var category; var marker; var color; if(bmi < 18.5){ category = "underweight"; color = "#1a73e8"; marker = Math.max(0,(bmi/18.5)*25); } else if(bmi < 25){ category = "normal"; color = "#1e8e5a"; marker = 25 + ((bmi-18.5)/6.5)*25; } else if(bmi < 30){ category = "overweight"; color = "#e6a700"; marker = 50 + ((bmi-25)/5)*20; } else{ category = "obese"; color = "#d63031"; marker = Math.min( 100, 70 + ((bmi-30)/10)*30 ); } id("BK_CATEGORY").setAttribute( "data-category", category ); id("BK_CATEGORY").style.background = color; id("BK_MARKER").style.left = Math.max(0,Math.min(marker,100)) + "%"; updateResult(); id("BK_RESULT").style.display = "block"; return; } /* ====================================================== STUDENT MODE WHO BMI-for-age CANNOT BE INTERPRETED USING ADULT 18.5 / 25 / 30 CUT-OFFS. ====================================================== */ id("BK_CATEGORY").removeAttribute( "data-category" ); id("BK_CATEGORY").style.background = "#1255a5"; if(lang === "hi"){ id("BK_CATEGORY").textContent = "उम्र और लिंग के अनुसार WHO आकलन"; id("BK_RESULT_NOTE").innerHTML = "विद्यार्थी BMI:
” + “BMI = ” + bmi.toFixed(1) + “

” + “5–19 वर्ष की उम्र में BMI की व्याख्या उम्र और लिंग के अनुसार WHO BMI-for-age reference से की जानी चाहिए। इस आयु में वयस्क 18.5 / 25 / 30 वाले कट-ऑफ सीधे लागू नहीं किए जाते।”; }else{ id(“BK_CATEGORY”).textContent = “WHO age & sex assessment”; id(“BK_RESULT_NOTE”).innerHTML = “Student BMI:
” + “BMI = ” + bmi.toFixed(1) + “

” + “For ages 5–19 years, BMI should be interpreted using the WHO BMI-for-age reference according to exact age and sex. Adult 18.5 / 25 / 30 cut-offs should not be directly applied to students.”; } id(“BK_RESULT”).style.display = “block”; }; })();

You may also like...

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.