Body Mass Index (BMI) & Healthy Weight Range Calculator

ANA›Life Services Authority›National Calculator Authority›Body Mass Index (BMI) & Healthy Weight Range Calculator

.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }

Body Mass Index (BMI) & Healthy Weight Range Calculator

Calculate your BMI and discover your healthy weight range. BMI is a widely used screening tool to categorize weight status relative to height.

Unit System

Metric (kg, cm) Imperial (lb, in)

Height (cm)

Weight (kg)

Height — Feet

Height — Inches

Weight (lb)

Age (years) (optional, for context)

Biological Sex (optional, for context)

Prefer not to say Male Female

Calculate BMI

### Your Results

Your BMI

Healthy Weight Range

BMI 18.5 – 24.9

Weight Status

BMI Scale

1018.5Under25Normal30Over40+Obese

Category BMI Range Status

#### Formula

Metric:

BMI = weight(kg) ÷ height(m)²

Imperial:

BMI = 703 × weight(lb) ÷ height(in)²

Healthy Weight Range (from height):

Min weight = 18.5 × height(m)² Max weight = 24.9 × height(m)²

BMI Categories (WHO standard):

#### Assumptions & References

function bodToggleUnits() { var sys = document.getElementById('bod-unit-system').value; document.getElementById('bod-metric-inputs').style.display = sys === 'metric' ? '' : 'none'; document.getElementById('bod-imperial-inputs').style.display = sys === 'imperial' ? '' : 'none'; document.getElementById('bod-result').style.display = 'none'; document.getElementById('bod-error').style.display = 'none'; }

function bodShowError(msg) { var el = document.getElementById('bod-error'); el.textContent = msg; el.style.display = 'block'; document.getElementById('bod-result').style.display = 'none'; }

function bodGetCategory(bmi) { if (bmi 300) { bodShowError('Height must be between 50 cm and 300 cm.'); return; } if (wkg 700) { bodShowError('Weight must be between 1 kg and 700 kg.'); return; } heightM = hcm / 100; weightKg = wkg; } else { var hft = parseFloat(document.getElementById('bod-height-ft').value) || 0; var hin = parseFloat(document.getElementById('bod-height-in').value) || 0; var wlb = parseFloat(document.getElementById('bod-weight-lb').value); if ((hft === 0 && hin === 0) || isNaN(hft)) { bodShowError('Please enter a valid height in feet and inches.'); return; } if (isNaN(wlb) || wlb 118) { bodShowError('Height must be between 1 ft 8 in and 9 ft 10 in.'); return; } if (wlb 1500) { bodShowError('Weight must be between 2 lb and 1500 lb.'); return; } heightM = totalIn * 0.0254; weightKg = wlb * 0.45359237; }

// Core BMI calculation var bmi = weightKg / (heightM * heightM);

// Healthy weight range (BMI 18.5 – 24.9) var minKg = 18.5 * heightM * heightM; var maxKg = 24.9 * heightM * heightM;

var cat = bodGetCategory(bmi);

// Weight difference from healthy range
var diffText = '';
if (bmi 24.9) {
var over = weightKg - maxKg;
diffText = sys === 'metric'
? 'You are ' + over.toFixed(1) + ' kg above the healthy range.'
'You are ' + (over / 0.45359237).toFixed(1) + ' lb above the healthy range.'; } else { diffText = 'You are within the healthy weight range. ✓'; }
// Format healthy range string
var rangeStr = sys === 'metric'
? minKg.toFixed(1) + ' – ' + maxKg.toFixed(1) + ' kg'
(minKg / 0.45359237).toFixed(1) + ' – ' + (maxKg / 0.45359237).toFixed(1) + ' lb';

// Gauge marker position (BMI scale 10–45, clamped) var gaugeMin = 10, gaugeMax = 45; var pct = Math.min(Math.max((bmi - gaugeMin) / (gaugeMax - gaugeMin) * 100, 1), 99); document.getElementById('bod-gauge-marker').style.left = 'calc(' + pct.toFixed(1) + '% - 2px)';

// Populate results document.getElementById('bod-bmi-value').textContent = bmi.toFixed(1); document.getElementById('bod-bmi-category').style.color = cat.color; document.getElementById('bod-bmi-category').textContent = cat.label; document.getElementById('bod-healthy-range').textContent = rangeStr; document.getElementById('bod-weight-diff').textContent = diffText; document.getElementById('bod-weight-diff').style.color = bmi >= 18.5 && bmi = c.min && bmi ' + '' + c.label + '' + '' + c.range + '' + '' + (isYou ? '◀ You' : '') + '' + ''; }); document.getElementById('bod-category-table').innerHTML = tableHTML;

// Context note var age = parseInt(document.getElementById('bod-age').value) || 0; var sex = document.getElementById('bod-sex').value; var note = 'BMI is a useful screening tool but does not account for muscle mass, bone density, or fat distribution. '; if (age >= 65) note += 'For older adults (65+), a BMI of 23–30 may be associated with better health outcomes. '; if (sex === 'female') note += 'Women typically have a higher body fat percentage than men at the same BMI. '; if (sex === 'male') note += 'Men typically have a lower body fat percentage than women at the same BMI. '; note += 'Consult a healthcare professional for a comprehensive health assessment.'; document.getElementById('bod-context-note').textContent = note;

document.getElementById('bod-result').style.display = 'block'; }

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References

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