Adult BMI Calculator ( 20 years+)
Adult BMI Calculator: A Complete Guide to Understanding Your Body Mass Index
What is BMI?
BMI, or Body Mass Index, is a widely used measurement to assess a person’s body fat based on their weight and height. It is a simple numerical value that helps determine if an individual is underweight, normal weight, overweight, or obese. The BMI formula is:
BMI = \frac{\text{weight (kg)}}{\text{height (m)}^2}
For those using pounds and inches:
BMI = \frac{\text{weight (lbs)} \times 703}{\text{height (in)}^2}
While BMI is not a perfect indicator of health, it provides a quick and easy way to gauge weight categories and potential health risks.
How to Use an Adult BMI Calculator?
An adult BMI calculator is a simple tool where you enter your weight and height to get an instant BMI result. Here’s how to use it:
1. Enter your weight – Choose between kilograms (kg) or pounds (lbs).
2. Enter your height – Select meters (m) or feet and inches (ft/in).
3. Click calculate – The tool will instantly compute your BMI.
4. Interpret your BMI result – Compare your BMI value with standard weight categories.
BMI Categories for Adults
According to the World Health Organization (WHO), BMI categories for adults (aged 18 and older) are:
Underweight: BMI < 18.5
Normal weight: BMI 18.5 – 24.9
Overweight: BMI 25 – 29.9
Obese (Class 1): BMI 30 – 34.9
Obese (Class 2): BMI 35 – 39.9
Obese (Class 3 – Severe Obesity): BMI ≥ 40
These categories help individuals assess their weight status and make informed decisions about their health.
Why is BMI Important?
BMI serves as a screening tool for potential health risks related to weight. Here’s why it matters:
1. Identifies weight-related health risks – High BMI is linked to conditions like heart disease, diabetes, and high blood pressure.
2. Aids in weight management – Knowing your BMI helps you set realistic weight goals.
3. Provides a general health indicator – While not a direct measure of body fat, BMI helps assess overall health trends.
Limitations of BMI
Although BMI is a useful tool, it has some limitations:
1. Doesn’t consider muscle mass – Athletes and bodybuilders may have high BMI due to muscle, not fat.
2. Ignores fat distribution – BMI doesn’t differentiate between fat stored in the belly (which is riskier) and fat stored elsewhere.
3. Not suitable for all populations – Pregnant women, elderly individuals, and certain ethnic groups may need different assessment methods.
How to Maintain a Healthy BMI?
If your BMI falls outside the normal range, here are some tips to achieve a healthy weight:
1. Eat a balanced diet – Focus on whole foods, lean proteins, healthy fats, and fiber-rich carbohydrates.
2. Exercise regularly – Aim for at least 150 minutes of moderate-intensity activity per week.
3. Stay hydrated – Drinking enough water supports metabolism and overall health.
4. Get enough sleep – Poor sleep is linked to weight gain and metabolic issues.
5. Monitor your progress – Regularly check your BMI and adjust lifestyle habits accordingly.
Frequently Asked Questions (FAQs)
1. What is a healthy BMI range for adults?
A BMI between 18.5 and 24.9 is considered normal for most adults.
2. Is BMI accurate for measuring body fat?
BMI gives a general estimate but doesn’t distinguish between muscle and fat, making it less accurate for athletes or older adults.
3. Can BMI be used for children?
No, BMI for children is interpreted differently based on age and gender.
4. How often should I check my BMI?
It’s a good idea to check your BMI every few months, especially if you’re trying to gain or lose weight.
5. What should I do if my BMI is too high?
Consult a doctor or nutritionist for personalized weight management advice.
#calc_wrapper{ --family-calc-vis:dm sans,sans-serif; --title-color:#fff; --values-color:#394f5c; --text-color:#000; } .toggle-switch { display: inline-block; position: relative; width: 30px; height: 17px; margin-left:15px; margin-top: 4px; } .toggle-switch input { display: none; } .toggle-switch-slider { position: absolute; cursor: pointer; top: 0; left: 0; right: 0; bottom: 0; background-color: #ccc; border-radius: 17px; transition: 0.4s; } .toggle-switch-slider:before { position: absolute; content: ""; height: 13px; width: 13px; left: 2px; bottom: 2px; background-color: white; border-radius: 50%; transition: 0.4s; } input:checked + .toggle-switch-slider { background-color: #4f94d4; } input:checked + .toggle-switch-slider:before { transform: translateX(13px); } .imperial_inputs{ display:none; }
');
$('#calc_input_button').addClass('re');
var bmi = (parseFloat(weight)/(parseInt(height)/100*parseInt(height)/100)).toFixed(2);
console.log(bmi);
if( bmi 12){
left = (bmi - 12)*($('.calc_info_line_underweight').width()/6.5);
console.log(left);
}
$('.calc_info_line_result_wrapper').css('left',(left-30)+'px' );
}
if(bmi >= 18.5 && bmi 18.5){
left = (bmi - 18.5)*($('.calc_info_line_healthy').width()/6.5);
}
$('.calc_info_line_result_wrapper').css('left',((left+$('.calc_info_line_underweight').width())-30)+'px' );
}
if(bmi >= 25 && bmi 25){
left = (bmi - 25)*($('.calc_info_line_overweight').width()/5);
}
$('.calc_info_line_result_wrapper').css('left',((left+$('.calc_info_line_underweight').width()+$('.calc_info_line_healthy').width())-30)+'px' );
}
if(bmi >= 30 ){
$('.calc_info_placeholder.e1740770561').css('display','none');
$('.calc_info_data.e1740770561').css('display','block');
$('#calc_bmi').html(bmi);
$('#calc_conclusion').html('Obese');
var left = 0;
if(bmi > 30){
left = (bmi - 30)*($('.calc_info_line_obese').width()/5);
}
if(bmi > 35){
left = $('.calc_info_line_obese').width();
}
$('.calc_info_line_result_wrapper').css('left',((left+$('.calc_info_line_underweight').width()+$('.calc_info_line_healthy').width() +$('.calc_info_line_overweight').width())-30)+'px' );
}
var healthy_min = Math.round(18.5 * (parseInt(height)/100*parseInt(height)/100));
var healthy_max = Math.round(24.99 * (parseInt(height)/100*parseInt(height)/100));
if(units == 'metric'){
$('#healthy_weight').html(healthy_min+' - '+healthy_max);
$('#calc_info_conclusionLb').css('display','none');
$('#calc_info_conclusion').css('display','block');
}else{
$('#healthy_weightLb').html(Math.round(healthy_min*2.20462)+' - '+Math.round(healthy_max*2.20462));
$('#calc_info_conclusionLb').css('display','block');
$('#calc_info_conclusion').css('display','none');
}
//$('#healthy_weightLb').html(Math.round(healthy_min*2.20462)+' - '+Math.round(healthy_max*2.20462));
}
}else{
var feets = $('#calc_height_input_ft').val();
var inches = $('#calc_height_input_in').val();
if(isNaN(parseFloat(feets))){
feets = 0;
}
if(isNaN(parseFloat(inches))){
inches = 0;
}
var height_imp = ((parseFloat(feets) + parseFloat(inches) / 12) * 30.48).toFixed(0);
if(height_imp 225 ){
$('.alert-mess[for="calc_height_input_ft"]').css('opacity','1');
$('#calc_height_input_ft').addClass('alert');
$('#calc_height_input_in').addClass('alert');
can = false;
}else{
$('.alert-mess[for="calc_height_input_ft"]').css('opacity','0');
$('#calc_height_input_ft').removeClass('alert');
$('#calc_height_input_in').removeClass('alert');
}
height = height_imp;
var pounds = $('#calc_weight_input_lb').val();
var stones = $('#calc_weight_input_st').val();
if(isNaN(parseFloat(pounds))){
pounds = 0;
}
if(isNaN(parseFloat(stones))){
stones = 0;
console.log('alo')
}
var weight_imp = ((parseFloat(pounds) + parseFloat(stones) / 14) / 2.20462 ).toFixed(0);
if(weight_imp 500){
$('.alert-mess[for="calc_weight_input_lb"]').css('opacity','1');
$('#calc_weight_input_lb').addClass('alert');
$('#calc_weight_input_st').addClass('alert');
can = false;
}else{
$('.alert-mess[for="calc_weight_input_lb"]').css('opacity','0');
$('#calc_weight_input_lb').removeClass('alert');
$('#calc_weight_input_st').removeClass('alert');
}
console.log(parseFloat(stones))
weight = weight_imp;
//console.log(can);
if(can){
$('#calc_input_button').html('Recalculate BMI ');
$('#calc_input_button').addClass('re');
var bmi = (parseFloat(weight)/(parseInt(height)/100*parseInt(height)/100)).toFixed(2);
console.log(bmi);
if( bmi 12){
left = (bmi - 12)*($('.calc_info_line_underweight').width()/6.5);
console.log(left);
}
$('.calc_info_line_result_wrapper').css('left',(left-30)+'px' );
}
if(bmi >= 18.5 && bmi 18.5){
left = (bmi - 18.5)*($('.calc_info_line_healthy').width()/6.5);
}
$('.calc_info_line_result_wrapper').css('left',((left+$('.calc_info_line_underweight').width())-30)+'px' );
}
if(bmi >= 25 && bmi 25){
left = (bmi - 25)*($('.calc_info_line_overweight').width()/5);
}
$('.calc_info_line_result_wrapper').css('left',((left+$('.calc_info_line_underweight').width()+$('.calc_info_line_healthy').width())-30)+'px' );
}
if(bmi >= 30 ){
$('.calc_info_placeholder.e1740770561').css('display','none');
$('.calc_info_data.e1740770561').css('display','block');
$('#calc_bmi').html(bmi);
$('#calc_conclusion').html('Obese');
var left = 0;
if(bmi > 30){
left = (bmi - 30)*($('.calc_info_line_obese').width()/5);
}
if(bmi > 35){
left = $('.calc_info_line_obese').width();
}
$('.calc_info_line_result_wrapper').css('left',((left+$('.calc_info_line_underweight').width()+$('.calc_info_line_healthy').width() +$('.calc_info_line_overweight').width())-30)+'px' );
}
var healthy_min = Math.round(18.5 * (parseInt(height)/100*parseInt(height)/100));
var healthy_max = Math.round(24.99 * (parseInt(height)/100*parseInt(height)/100));
if(units == 'metric'){
$('#healthy_weight').html(healthy_min+' - '+healthy_max);
$('#calc_info_conclusionLb').css('display','none');
$('#calc_info_conclusion').css('display','block');
}else{
$('#healthy_weightLb').html(Math.round(healthy_min*2.20462)+' - '+Math.round(healthy_max*2.20462));
$('#calc_info_conclusionLb').css('display','block');
$('#calc_info_conclusion').css('display','none');
}
}
}
break;
}
}
function check_imperial(can){
var feets = $('#calc_height_input_ft').val();
var inches = $('#calc_height_input_in').val();
if(isNaN(parseFloat(feets))){
feets = 0;
}
if(isNaN(parseFloat(inches))){
inches = 0;
}
var height_imp = ((parseFloat(feets) + parseFloat(inches) / 12) * 30.48).toFixed(0);
if(height_imp 225 ){
$('.alert-mess[for="calc_height_input_ft"]').css('opacity','1');
$('#calc_height_input_ft').addClass('alert');
$('#calc_height_input_in').addClass('alert');
can = false;
}else{
$('.alert-mess[for="calc_height_input_ft"]').css('opacity','0');
$('#calc_height_input_ft').removeClass('alert');
$('#calc_height_input_in').removeClass('alert');
}
height = height_imp;
var pounds = $('#calc_weight_input_lb').val();
var stones = $('#calc_weight_input_st').val();
if(isNaN(parseFloat(pounds))){
pounds = 0;
}
if(isNaN(parseFloat(stones))){
stones = 0;
console.log('alo')
}
var weight_imp = ((parseFloat(pounds) + parseFloat(stones) / 14) / 2.20462 ).toFixed(0);
if(weight_imp 500){
$('.alert-mess[for="calc_weight_input_lb"]').css('opacity','1');
$('#calc_weight_input_lb').addClass('alert');
$('#calc_weight_input_st').addClass('alert');
can = false;
}else{
$('.alert-mess[for="calc_weight_input_lb"]').css('opacity','0');
$('#calc_weight_input_lb').removeClass('alert');
$('#calc_weight_input_st').removeClass('alert');
}
console.log(parseFloat(stones))
weight = weight_imp;
return can;
}
addEventListener("keydown", moveRect);
const fweight = x => ( (x.toString().includes('.')) ? (x.toString().split('.').pop().length) : (0) );
var height = '';
var weight = '';
var checkingRegExp = new RegExp(/^(\d)$/g);
$('#calc_height_input').on('input',function(){
if(/^[\d.]*$/.test($(this).val()) && $(this).val().split(".").length < 3){
height = $(this).val();
}else{
$(this).val(height);
}
if(parseInt($(this).val()) 225 || !Number.isInteger(parseInt($(this).val())) || $(this).val()[0]=='0'){
$('.alert-mess[for="'+$(this).attr('id')+'"]').css('opacity','1');
$(this).addClass('alert');
}else{
$('.alert-mess[for="'+$(this).attr('id')+'"]').css('opacity','0');
$(this).removeClass('alert');
}
})
$('#calc_weight_input').on('input',function(){
if(/^[\d.]*$/.test($(this).val()) && $(this).val().split(".").length < 3 ){
weight = $(this).val();
}else{
$(this).val(weight);
}
if(parseFloat($(this).val()) 500 || fweight(parseFloat($(this).val())) > 1 || parseFloat($(this).val())!=$(this).val() || $(this).val()[0]=='0'){
$('.alert-mess[for="'+$(this).attr('id')+'"]').css('opacity','1');
$(this).addClass('alert');
can = false;
}else{
$('.alert-mess[for="'+$(this).attr('id')+'"]').css('opacity','0');
$(this).removeClass('alert');
}
})
var prev1 = 0;
var prev2 = 0;
var prev3 = 0;
var prev4 = 0;
$('#calc_height_input_ft').on('input',function(){
if(/^[\d.]*$/.test($(this).val())){
prev1 = $(this).val();
}else{
$(this).val(prev1);
}
var can = check_imperial(true);
})
$('#calc_height_input_in').on('input',function(){
if(/^[\d.]*$/.test($(this).val())){
prev2 = $(this).val();
}else{
$(this).val(prev2);
}
var can = check_imperial(true);
})
$('#calc_weight_input_lb').on('input',function(){
if(/^[\d.]*$/.test($(this).val())){
prev3 = $(this).val();
}else{
$(this).val(prev3);
}
var can = check_imperial(true);
})
$('#calc_weight_input_st').on('input',function(){
if(/^[\d.]*$/.test($(this).val())){
prev4 = $(this).val();
}else{
$(this).val(prev4);
}
var can = check_imperial(true);
})
$('#calc_input_button').on('click',function(){
var can = true;
if(units == 'metric'){
$('#calc_height_input').each(function(){
if(parseInt($(this).val()) 225 || !Number.isInteger(parseInt($(this).val())) || $(this).val()[0]=='0'){
$('.alert-mess[for="'+$(this).attr('id')+'"]').css('opacity','1');
$(this).addClass('alert');
can = false;
}else{
$('.alert-mess[for="'+$(this).attr('id')+'"]').css('opacity','0');
$(this).removeClass('alert');
height = $(this).val();
}
})
$('#calc_weight_input').each(function(){
if(parseFloat($(this).val()) 500 || fweight(parseFloat($(this).val())) > 1 || parseFloat($(this).val())!=$(this).val() || $(this).val()[0]=='0'){
$('.alert-mess[for="'+$(this).attr('id')+'"]').css('opacity','1');
$(this).addClass('alert');
can = false;
}else{
$('.alert-mess[for="'+$(this).attr('id')+'"]').css('opacity','0');
$(this).removeClass('alert');
weight = $(this).val();
}
})
}else{
if(can){
can = check_imperial(true);
}
}
//console.log(can);
if(can){
$('#calc_input_button').html('Recalculate BMI ');
$('#calc_input_button').addClass('re');
console.log(weight)
console.log(height)
var bmi = (parseFloat(weight)/(parseInt(height)/100*parseInt(height)/100)).toFixed(2);
console.log(bmi);
if( bmi 12){
left = (bmi - 12)*($('.calc_info_line_underweight').width()/6.5);
console.log(left);
}
$('.calc_info_line_result_wrapper').css('left',(left-30)+'px' );
}
if(bmi >= 18.5 && bmi 18.5){
left = (bmi - 18.5)*($('.calc_info_line_healthy').width()/6.5);
}
$('.calc_info_line_result_wrapper').css('left',((left+$('.calc_info_line_underweight').width())-30)+'px' );
}
if(bmi >= 25 && bmi 25){
left = (bmi - 25)*($('.calc_info_line_overweight').width()/5);
}
$('.calc_info_line_result_wrapper').css('left',((left+$('.calc_info_line_underweight').width()+$('.calc_info_line_healthy').width())-30)+'px' );
}
if(bmi >= 30 ){
$('.calc_info_placeholder.e1740770561').css('display','none');
$('.calc_info_data.e1740770561').css('display','block');
$('#calc_bmi').html(bmi);
$('#calc_conclusion').html('Obese');
var left = 0;
if(bmi > 30){
left = (bmi - 30)*($('.calc_info_line_obese').width()/5);
}
if(bmi > 35){
left = $('.calc_info_line_obese').width();
}
$('.calc_info_line_result_wrapper').css('left',((left+$('.calc_info_line_underweight').width()+$('.calc_info_line_healthy').width() +$('.calc_info_line_overweight').width())-30)+'px' );
}
var healthy_min = Math.round(18.5 * (parseInt(height)/100*parseInt(height)/100));
var healthy_max = Math.round(24.99 * (parseInt(height)/100*parseInt(height)/100));
if(units == 'metric'){
$('#healthy_weight').html(healthy_min+' - '+healthy_max);
$('#calc_info_conclusionLb').css('display','none');
$('#calc_info_conclusion').css('display','block');
}else{
$('#healthy_weightLb').html(Math.round(healthy_min*2.20462)+' - '+Math.round(healthy_max*2.20462));
$('#calc_info_conclusionLb').css('display','block');
$('#calc_info_conclusion').css('display','none');
}
}
})
})( jQuery );
})