BMI Calculator
Get a comprehensive health snapshot with this BMI calculator. Enter your height and weight in imperial or metric units to calculate your Body Mass Index and see which category you fall into. The calculator also shows your healthy weight range for your height, estimates daily calorie needs based on activity level, and provides personalized recommendations. Perfect for fitness websites, health clinics, gyms, and wellness apps.
Try the Calculator
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export function bmiCalculator(form: FormTs) {
form.addRow(row => {
row.addTextPanel('header', {
computedValue: () => 'BMI Calculator',
customStyles: { 'font-size': '1.5rem', 'font-weight': '600', 'color': '#1e293b' }
});
});
form.addSpacer({ height: 20 });
// Measurement System Section
const systemSection = form.addSubform('system', { title: '📐 Measurement System' });
systemSection.addRow(row => {
row.addRadioButton('units', {
label: 'Select Units',
options: [
{ id: 'imperial', name: 'Imperial (lbs, ft/in)' },
{ id: 'metric', name: 'Metric (kg, cm)' }
],
defaultValue: 'imperial',
isRequired: true
});
});
// Body Measurements Section
const measurementsSection = form.addSubform('measurements', { title: '⚖️ Your Measurements' });
// Imperial inputs
measurementsSection.addRow(row => {
row.addInteger('heightFeet', {
label: 'Height (feet)',
min: 3,
max: 8,
defaultValue: 5,
suffix: 'ft',
isRequired: true,
isVisible: () => systemSection.radioButton('units')?.value() === 'imperial'
}, '1fr');
row.addInteger('heightInches', {
label: 'Height (inches)',
min: 0,
max: 11,
defaultValue: 9,
suffix: 'in',
isRequired: true,
isVisible: () => systemSection.radioButton('units')?.value() === 'imperial'
}, '1fr');
});
measurementsSection.addRow(row => {
row.addDecimal('weightLbs', {
label: 'Weight',
min: 50,
max: 700,
defaultValue: 160,
suffix: 'lbs',
isRequired: true,
isVisible: () => systemSection.radioButton('units')?.value() === 'imperial'
});
});
// Metric inputs
measurementsSection.addRow(row => {
row.addInteger('heightCm', {
label: 'Height',
min: 100,
max: 250,
defaultValue: 175,
suffix: 'cm',
isRequired: true,
isVisible: () => systemSection.radioButton('units')?.value() === 'metric'
});
});
measurementsSection.addRow(row => {
row.addDecimal('weightKg', {
label: 'Weight',
min: 25,
max: 320,
defaultValue: 72,
suffix: 'kg',
isRequired: true,
isVisible: () => systemSection.radioButton('units')?.value() === 'metric'
});
});
// Additional Info Section
const infoSection = form.addSubform('info', { title: '👤 Additional Information' });
infoSection.addRow(row => {
row.addDropdown('ageGroup', {
label: 'Age Group',
options: [
{ id: 'child', name: 'Child (2-17 years)' },
{ id: 'adult', name: 'Adult (18-64 years)' },
{ id: 'senior', name: 'Senior (65+ years)' }
],
defaultValue: 'adult'
}, '1fr');
row.addDropdown('sex', {
label: 'Sex',
options: [
{ id: 'male', name: 'Male' },
{ id: 'female', name: 'Female' }
],
defaultValue: 'male',
tooltip: 'Used for healthy weight range recommendations'
}, '1fr');
});
infoSection.addRow(row => {
row.addDropdown('activityLevel', {
label: 'Activity Level',
options: [
{ id: 'sedentary', name: 'Sedentary (little/no exercise)' },
{ id: 'light', name: 'Light (exercise 1-3 days/week)' },
{ id: 'moderate', name: 'Moderate (exercise 3-5 days/week)' },
{ id: 'active', name: 'Active (exercise 6-7 days/week)' },
{ id: 'very-active', name: 'Very Active (intense daily exercise)' }
],
defaultValue: 'moderate',
tooltip: 'Used for calorie recommendations'
});
});
form.addSpacer({ height: 20, showLine: true, lineStyle: 'dashed' });
// Results Section
const resultsSection = form.addSubform('results', { title: '📊 Your Results', isCollapsible: false });
resultsSection.addRow(row => {
row.addPriceDisplay('bmiValue', {
label: 'Your BMI',
computedValue: () => {
const units = systemSection.radioButton('units')?.value() || 'imperial';
let heightM: number;
let weightKg: number;
if (units === 'imperial') {
const feet = measurementsSection.integer('heightFeet')?.value() || 5;
const inches = measurementsSection.integer('heightInches')?.value() || 9;
const weightLbs = measurementsSection.decimal('weightLbs')?.value() || 160;
const totalInches = (feet * 12) + inches;
heightM = totalInches * 0.0254;
weightKg = weightLbs * 0.453592;
} else {
heightM = (measurementsSection.integer('heightCm')?.value() || 175) / 100;
weightKg = measurementsSection.decimal('weightKg')?.value() || 72;
}
const bmi = weightKg / (heightM * heightM);
return Math.round(bmi * 10) / 10;
},
variant: 'large',
prefix: '',
suffix: ''
});
});
resultsSection.addRow(row => {
row.addTextPanel('bmiCategory', {
computedValue: () => {
const units = systemSection.radioButton('units')?.value() || 'imperial';
let heightM: number;
let weightKg: number;
if (units === 'imperial') {
const feet = measurementsSection.integer('heightFeet')?.value() || 5;
const inches = measurementsSection.integer('heightInches')?.value() || 9;
const weightLbs = measurementsSection.decimal('weightLbs')?.value() || 160;
const totalInches = (feet * 12) + inches;
heightM = totalInches * 0.0254;
weightKg = weightLbs * 0.453592;
} else {
heightM = (measurementsSection.integer('heightCm')?.value() || 175) / 100;
weightKg = measurementsSection.decimal('weightKg')?.value() || 72;
}
const bmi = weightKg / (heightM * heightM);
if (bmi < 18.5) return 'Category: Underweight';
if (bmi < 25) return 'Category: Normal Weight';
if (bmi < 30) return 'Category: Overweight';
if (bmi < 35) return 'Category: Obese (Class I)';
if (bmi < 40) return 'Category: Obese (Class II)';
return 'Category: Obese (Class III)';
},
customStyles: { 'font-size': '1.1rem', 'font-weight': '600', 'text-align': 'center', 'color': '#1e293b' }
});
});
resultsSection.addSpacer({ height: 15 });
resultsSection.addRow(row => {
row.addTextPanel('bmiScale', {
computedValue: () => {
return 'BMI Categories: Underweight (<18.5) | Normal (18.5-24.9) | Overweight (25-29.9) | Obese (30+)';
},
customStyles: { 'font-size': '0.85rem', 'color': '#64748b', 'text-align': 'center' }
});
});
// Healthy Weight Range Section
const rangeSection = form.addSubform('range', { title: '🎯 Healthy Weight Range', isCollapsible: false });
rangeSection.addRow(row => {
row.addPriceDisplay('minHealthyWeight', {
label: 'Minimum Healthy Weight',
computedValue: () => {
const units = systemSection.radioButton('units')?.value() || 'imperial';
let heightM: number;
if (units === 'imperial') {
const feet = measurementsSection.integer('heightFeet')?.value() || 5;
const inches = measurementsSection.integer('heightInches')?.value() || 9;
const totalInches = (feet * 12) + inches;
heightM = totalInches * 0.0254;
} else {
heightM = (measurementsSection.integer('heightCm')?.value() || 175) / 100;
}
const minWeightKg = 18.5 * heightM * heightM;
if (units === 'imperial') {
return Math.round(minWeightKg / 0.453592);
}
return Math.round(minWeightKg);
},
variant: 'default',
prefix: '',
suffix: () => systemSection.radioButton('units')?.value() === 'imperial' ? ' lbs' : ' kg'
}, '1fr');
row.addPriceDisplay('maxHealthyWeight', {
label: 'Maximum Healthy Weight',
computedValue: () => {
const units = systemSection.radioButton('units')?.value() || 'imperial';
let heightM: number;
if (units === 'imperial') {
const feet = measurementsSection.integer('heightFeet')?.value() || 5;
const inches = measurementsSection.integer('heightInches')?.value() || 9;
const totalInches = (feet * 12) + inches;
heightM = totalInches * 0.0254;
} else {
heightM = (measurementsSection.integer('heightCm')?.value() || 175) / 100;
}
const maxWeightKg = 24.9 * heightM * heightM;
if (units === 'imperial') {
return Math.round(maxWeightKg / 0.453592);
}
return Math.round(maxWeightKg);
},
variant: 'default',
prefix: '',
suffix: () => systemSection.radioButton('units')?.value() === 'imperial' ? ' lbs' : ' kg'
}, '1fr');
});
rangeSection.addRow(row => {
row.addTextPanel('weightDifference', {
computedValue: () => {
const units = systemSection.radioButton('units')?.value() || 'imperial';
let heightM: number;
let currentWeightKg: number;
if (units === 'imperial') {
const feet = measurementsSection.integer('heightFeet')?.value() || 5;
const inches = measurementsSection.integer('heightInches')?.value() || 9;
const weightLbs = measurementsSection.decimal('weightLbs')?.value() || 160;
const totalInches = (feet * 12) + inches;
heightM = totalInches * 0.0254;
currentWeightKg = weightLbs * 0.453592;
} else {
heightM = (measurementsSection.integer('heightCm')?.value() || 175) / 100;
currentWeightKg = measurementsSection.decimal('weightKg')?.value() || 72;
}
const bmi = currentWeightKg / (heightM * heightM);
const minWeightKg = 18.5 * heightM * heightM;
const maxWeightKg = 24.9 * heightM * heightM;
if (bmi >= 18.5 && bmi <= 24.9) {
return 'Your weight is within the healthy range for your height.';
} else if (bmi < 18.5) {
const diff = minWeightKg - currentWeightKg;
const diffDisplay = units === 'imperial' ? Math.round(diff / 0.453592) + ' lbs' : Math.round(diff) + ' kg';
return `You are ${diffDisplay} below the healthy range.`;
} else {
const diff = currentWeightKg - maxWeightKg;
const diffDisplay = units === 'imperial' ? Math.round(diff / 0.453592) + ' lbs' : Math.round(diff) + ' kg';
return `You are ${diffDisplay} above the healthy range.`;
}
},
customStyles: { 'font-size': '0.95rem', 'color': '#475569', 'text-align': 'center', 'font-weight': '500' }
});
});
// Daily Calories Section
const caloriesSection = form.addSubform('calories', { title: '🔥 Daily Calorie Needs', isCollapsible: false });
caloriesSection.addRow(row => {
row.addPriceDisplay('bmr', {
label: 'Basal Metabolic Rate (BMR)',
computedValue: () => {
const units = systemSection.radioButton('units')?.value() || 'imperial';
const sex = infoSection.dropdown('sex')?.value() || 'male';
let heightCm: number;
let weightKg: number;
if (units === 'imperial') {
const feet = measurementsSection.integer('heightFeet')?.value() || 5;
const inches = measurementsSection.integer('heightInches')?.value() || 9;
const weightLbs = measurementsSection.decimal('weightLbs')?.value() || 160;
heightCm = ((feet * 12) + inches) * 2.54;
weightKg = weightLbs * 0.453592;
} else {
heightCm = measurementsSection.integer('heightCm')?.value() || 175;
weightKg = measurementsSection.decimal('weightKg')?.value() || 72;
}
// Using Mifflin-St Jeor equation with estimated age of 30
const age = 30;
let bmr: number;
if (sex === 'male') {
bmr = (10 * weightKg) + (6.25 * heightCm) - (5 * age) + 5;
} else {
bmr = (10 * weightKg) + (6.25 * heightCm) - (5 * age) - 161;
}
return Math.round(bmr);
},
variant: 'default',
prefix: '',
suffix: ' cal',
tooltip: 'Calories burned at rest'
}, '1fr');
row.addPriceDisplay('tdee', {
label: 'Daily Calorie Needs (TDEE)',
computedValue: () => {
const units = systemSection.radioButton('units')?.value() || 'imperial';
const sex = infoSection.dropdown('sex')?.value() || 'male';
const activity = infoSection.dropdown('activityLevel')?.value() || 'moderate';
let heightCm: number;
let weightKg: number;
if (units === 'imperial') {
const feet = measurementsSection.integer('heightFeet')?.value() || 5;
const inches = measurementsSection.integer('heightInches')?.value() || 9;
const weightLbs = measurementsSection.decimal('weightLbs')?.value() || 160;
heightCm = ((feet * 12) + inches) * 2.54;
weightKg = weightLbs * 0.453592;
} else {
heightCm = measurementsSection.integer('heightCm')?.value() || 175;
weightKg = measurementsSection.decimal('weightKg')?.value() || 72;
}
const age = 30;
let bmr: number;
if (sex === 'male') {
bmr = (10 * weightKg) + (6.25 * heightCm) - (5 * age) + 5;
} else {
bmr = (10 * weightKg) + (6.25 * heightCm) - (5 * age) - 161;
}
const activityMultipliers: Record<string, number> = {
'sedentary': 1.2,
'light': 1.375,
'moderate': 1.55,
'active': 1.725,
'very-active': 1.9
};
return Math.round(bmr * (activityMultipliers[activity] || 1.55));
},
variant: 'success',
prefix: '',
suffix: ' cal',
tooltip: 'Total Daily Energy Expenditure'
}, '1fr');
});
// Summary Section
const summarySection = form.addSubform('summary', {
title: '📋 Summary',
isCollapsible: false,
sticky: 'bottom'
});
summarySection.addRow(row => {
row.addTextPanel('recommendation', {
computedValue: () => {
const units = systemSection.radioButton('units')?.value() || 'imperial';
let heightM: number;
let weightKg: number;
if (units === 'imperial') {
const feet = measurementsSection.integer('heightFeet')?.value() || 5;
const inches = measurementsSection.integer('heightInches')?.value() || 9;
const weightLbs = measurementsSection.decimal('weightLbs')?.value() || 160;
const totalInches = (feet * 12) + inches;
heightM = totalInches * 0.0254;
weightKg = weightLbs * 0.453592;
} else {
heightM = (measurementsSection.integer('heightCm')?.value() || 175) / 100;
weightKg = measurementsSection.decimal('weightKg')?.value() || 72;
}
const bmi = weightKg / (heightM * heightM);
if (bmi < 18.5) {
return 'Consider consulting a healthcare provider about healthy weight gain strategies.';
} else if (bmi < 25) {
return 'Great! Maintain your healthy weight with balanced nutrition and regular exercise.';
} else if (bmi < 30) {
return 'Consider lifestyle changes including diet and exercise to reach a healthier weight.';
} else {
return 'We recommend consulting a healthcare provider for personalized weight management advice.';
}
},
customStyles: { 'font-size': '0.95rem', 'color': '#475569', 'text-align': 'center', 'font-weight': '500' }
});
});
summarySection.addRow(row => {
row.addTextPanel('disclaimer', {
computedValue: () => 'BMI is a general indicator and may not apply to athletes, elderly, or pregnant women. Consult a healthcare professional for personalized advice.',
customStyles: { 'font-size': '0.8rem', 'color': '#64748b', 'text-align': 'center' }
});
});
form.configureSubmitButton({
label: 'Save Results'
});
}
Frequently Asked Questions
What is a healthy BMI range?
A healthy BMI is between 18.5 and 24.9. Below 18.5 is considered underweight, 25-29.9 is overweight, and 30 or above is classified as obese. However, BMI doesn't account for muscle mass or body composition.
Is BMI accurate for everyone?
BMI is a useful screening tool but has limitations. It may overestimate body fat in athletes and muscular individuals, and underestimate it in older persons. Waist circumference and body fat percentage provide additional insights.
What is TDEE?
TDEE (Total Daily Energy Expenditure) is the total number of calories you burn daily, including your basal metabolic rate plus physical activity. This is the number of calories needed to maintain your current weight.
How can I lose weight safely?
A safe rate of weight loss is 1-2 pounds per week, achieved by creating a 500-1000 calorie daily deficit through diet and exercise. Consult a healthcare provider before starting any weight loss program.
Can I customize this calculator for my fitness website?
Yes, the calculator is fully customizable. Adjust the styling, add your branding, modify recommendations, and embed it on your health or fitness website to engage visitors.