Power Calculators

⚖️ BMI Calculator

5.0 out of 5 (3 ratings)

Enter details

📏 How to measure height at homeTap to see the illustrated guide
Illustration: how to measure height at home — Stand barefoot on a hard floor with heels, bottom and shoulders against a wall, looking straight ahead. Rest a hardback book or ruler flat on top of the head, touching the wall, and mark underneath it.
  1. Stand barefoot on a hard floor with heels, bottom and shoulders against a wall, looking straight ahead.
  2. Rest a hardback book or ruler flat on top of the head, touching the wall, and mark underneath it.
  3. Measure from the floor to the mark with a steel tape. Children from age 2 are measured standing like this.
Barefoot, back against a wall, book flat on your head.

Fill in the details and click Calculate to see your results.

Formula at a glance

BMI Calculator formula: BMI = Weight (kg) ÷ [Height (m)]²; Weight = 18.5 × Height² to 24.9 × Height²
How the bmi calculator works: BMI = Weight (kg) ÷ [Height (m)]²

📱 Also in our Android app

This calculator is also in our free app. Sign in with the same account to keep your history in sync.

  • Pregnancy, Period & Ovulation CalculatorsDue date, ovulation, period & pregnancy week calculatorsGet it on Google Play

Rate this calculator

Was it useful? A quick star rating helps others — and you can leave a comment too.
Rate it: ★ ★ ★ ★ ★

📘 About the BMI Calculator

Body Mass Index (BMI) relates your weight to your height: BMI = weight in kg ÷ (height in metres)². It is the most widely used first check of whether your weight is in a healthy range for your height.

Enter your weight in kilograms and height in centimetres. The result shows your BMI, its category under the World Health Organization (WHO) scale and under the lower Asian-Indian cut-offs, the healthy weight range for your height, and how much to lose or gain to reach it.

BMI does not measure body fat directly — muscular people can show a high BMI — so pair it with your waist measurement for a fuller picture.

🧮 Formula

BMI
BMI = Weight (kg) ÷ [Height (m)]²
Healthy weight range
Weight = 18.5 × Height² to 24.9 × Height²

Where

  • Height in metres = height in cm ÷ 100
  • In pounds and inches: BMI = 703 × weight (lb) ÷ [height (in)]²

✏️ Worked examples

70 kg and 170 cm

You enter
Weight70 kg
Height170 cm
You get
Your BMI24.2 kg/m²
BMI category (WHO)Normal (healthy weight)
Category with Asian / Indian cut-offsOverweight
Healthy weight for your height53.5 – 72 kg
To reach a healthy BMIYou are within the healthy range
BMI Prime (BMI ÷ 25)0.97
Your height170 cm (5 ft 7 in)
Your weight70 kg (154.3 lb)

BMI 24.2 kg/m² — Normal (healthy weight). Healthy weight at this height: 53.5 – 72 kg.

Try this example →

85 kg and 175 cm

You enter
Weight85 kg
Height175 cm
You get
Your BMI27.8 kg/m²
BMI category (WHO)Overweight
Category with Asian / Indian cut-offsObese
Healthy weight for your height56.7 – 76.3 kg
To reach a healthy BMILose about 8.7 kg to reach BMI 24.9
BMI Prime (BMI ÷ 25)1.11
Your height175 cm (5 ft 9 in)
Your weight85 kg (187.4 lb)

BMI 27.8 kg/m² — Overweight. Lose about 8.7 kg to reach BMI 24.9.

Try this example →

50 kg and 165 cm

You enter
Weight50 kg
Height165 cm
You get
Your BMI18.4 kg/m²
BMI category (WHO)Underweight
Category with Asian / Indian cut-offsUnderweight
Healthy weight for your height50.4 – 67.8 kg
To reach a healthy BMIGain about 0.4 kg to reach BMI 18.5
BMI Prime (BMI ÷ 25)0.73
Your height165 cm (5 ft 5 in)
Your weight50 kg (110.2 lb)

BMI 18.4 kg/m² — Underweight. Gain about 0.4 kg to reach BMI 18.5.

Try this example →

🧭 How to use this calculator

What you enter

  • Weight (kg)
  • Height (cm)Barefoot, back against a wall, book flat on your head.

What you get

  • BMI
  • Healthy Weight From (kg)
  • Healthy Weight To (kg)
  • BMI Prime

💡 BMI chart for adults (WHO)

  • Below 18.5 — Underweight
  • 18.5 to 24.9 — Normal (healthy) weight
  • 25 to 29.9 — Overweight
  • 30 to 34.9 — Obese Class I
  • 35 to 39.9 — Obese Class II
  • 40 and above — Obese Class III

💡 BMI cut-offs for Indians and Asians

  • Below 18.5 — Underweight
  • 18.5 to 22.9 — Normal
  • 23 to 24.9 — Overweight
  • 25 and above — Obese
  • These lower cut-offs are used in India because diabetes and heart-disease risk rise at a lower BMI in South Asians.

💡 How to calculate BMI by hand

Convert your height to metres, square it, and divide your weight by that number. Example: 70 kg and 1.70 m → 1.70 × 1.70 = 2.89 → 70 ÷ 2.89 = 24.2.

❓ Frequently asked questions

What is a normal BMI?

For adults a BMI from 18.5 to 24.9 is normal on the WHO scale. For Indians and other Asians, 18.5 to 22.9 is considered normal.

How is BMI calculated?

BMI = weight in kilograms divided by height in metres squared. For 70 kg and 1.70 m: 70 ÷ (1.70 × 1.70) = 24.2.

What is my healthy weight for my height?

Multiply your height in metres squared by 18.5 and by 24.9. At 170 cm that is 53.5 kg to 72 kg. The calculator shows this range for you.

Is BMI accurate for athletes?

No. Muscle is heavier than fat, so muscular people can have a high BMI without excess fat. Waist size or a body fat test gives a better picture.

Does BMI differ for men and women?

The same BMI categories are used for adult men and women, though women usually carry more body fat at the same BMI.

Is BMI valid for children?

Not with these adult categories. Children and teens under 18 need BMI-for-age percentile charts.

What is BMI Prime?

BMI Prime is your BMI divided by 25, the upper limit of normal. A value above 1.0 means overweight.

What people are saying
★★★★★
Anonymous · 05 Oct 2026
★★★★★
Anonymous · 04 Oct 2026
★★★★★
Anonymous · 30 Sep 2026