BMI & calorie calculator. Know your daily numbers.

How to use the BMI & Calorie Calculator

This calculator gives you four numbers from one short form: your body mass index, your resting calorie burn (BMR), your daily maintenance calories (TDEE) and calorie targets for losing or gaining weight. BMI is your weight divided by your height squared, and BMR uses the Mifflin-St Jeor equation. It is meant for healthy adults who want a quick estimate, not a diagnosis.

Step by step

1. 1
   Pick your units

   Under Units, choose Metric for centimeters and kilograms, or Imperial for feet, inches and pounds. Metric is selected when the page opens. Switching swaps the height fields and the weight label, and every result recomputes at once.

2. 2
   Choose sex for the BMR formula

   Under Sex (for BMR), choose Male or Female. It does not change your BMI. It only changes the BMR constant (plus 5 for male, minus 161 for female) and the lowest calorie target the tool will show.

3. 3
   Enter height and weight

   Type your Height and Weight. In Imperial mode, height has two boxes, one for feet and one for inches. Your BMI, its category and your healthy weight range appear as soon as both values are filled in. There is no button to press.

4. 4
   Add your age

   Type your Age in years. Until you do, the Daily calorie needs card only asks for it. Once age is filled in, the card shows your maintenance calories and the four targets.

5. 5
   Set your activity level

   Open Activity level and pick the line that matches a normal week, from Sedentary (multiplier 1.2) to Very active (1.9). Light, exercise 1-3 days/week (1.375) is selected by default. BMR times this multiplier is your TDEE.

Reading the result

• The large number under Body mass index is your BMI to one decimal place. The badge names the category: Underweight below 18.5, Healthy weight from 18.5 to under 25, Overweight from 25 to under 30, then Obese class I, II and III at 30, 35 and 40.
• The colored bar runs from 15 to 40 and the white marker shows where you sit. A BMI above 40 pins the marker to the right end.
• The sentence under the bar gives a healthy weight range for your height, using a BMI of 18.5 to 24.9. Worked example: 175 cm and 72 kg give a BMI of 23.5, Healthy weight, with a range of about 56.7 kg to 76.3 kg.
• The big number on the Daily calorie needs card is your TDEE in kcal per day. With the same 175 cm and 72 kg, age 30, Male and the default Light activity, BMR is 1,669 kcal and TDEE is 2,295 kcal.
• Mild loss is TDEE minus 250 kcal, Weight loss is minus 500, Maintain is TDEE itself and Weight gain is plus 500. In the example that is 2,045, 1,795, 2,295 and 2,795.
• If a loss target would drop below 1,500 kcal for Male or 1,200 kcal for Female, the tool shows that floor instead and labels it below safe minimum, capped.

Tips and common mistakes

• In Imperial mode, put whole feet in the ft box and the rest in the in box. 5 ft 9 in is 5 and 9, not 5.9 in the feet box.
• BMI cannot tell muscle from fat. A muscular person can read as Overweight while being lean, so treat the category as a rough guide.
• Pick the activity level for a typical week, not your best week. Most people overestimate it, which inflates every calorie target.
• The weekly rates under each target are written in kg, about 0.25 kg or 0.5 kg per week, even when you use Imperial units.
• These are estimates for healthy adults and not medical advice. Talk to a doctor or dietitian before you change your diet.

Privacy and limits

Every number is calculated by your own browser as you type. Nothing is sent to a server and nothing is saved, so reloading the page clears the form. Once the page has loaded, the calculator also works without a connection.

Back to the tool

One form, four answers.

• Calculate your BMI and see exactly which weight category you fall into on a colour-coded 15-40 scale.
• Find your healthy weight range for your height, shown in kg or lb to match your units.
• Estimate your resting calorie burn (BMR) using the clinically validated Mifflin-St Jeor equation.
• Get your TDEE, total daily energy expenditure, from five activity levels, sedentary to very active.
• See four calorie targets at once: mild loss, weight loss, maintain and weight gain, with unsafe deficits capped automatically.
• Switch between metric and imperial instantly, results recompute the moment you toggle or type.

Digital Heroes built this calculator. Planning a health app of your own? Our healthcare software work explains what we build and what we leave out.

Frequently asked questions.

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