How to Calculate Daily Calorie Needs (TDEE, Free)

Whether you want to lose fat, build muscle or simply maintain, every plan starts with one number: how many calories your body burns in a day. Guessing leads to slow progress or none at all. This guide explains BMR and TDEE, the proven Mifflin-St Jeor formula, and how activity changes the result. To get your number in seconds, use the free Calorie Calculator — it estimates your maintenance calories from your age, sex, height, weight and activity, and runs privately in your browser.

BMR, TDEE and the formula

Two terms matter here. BMR (basal metabolic rate) is the energy your body uses at complete rest just to stay alive. TDEE (total daily energy expenditure) is BMR plus everything you do — walking, working, exercising.

The Mifflin-St Jeor equation is the most accurate widely used BMR formula:

• Men: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5
• Women: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161

Your TDEE is then BMR multiplied by an activity factor.

How to use the Calorie Calculator

No equations required:

1. Open the Calorie Calculator.
2. Select your sex.
3. Enter your age, height and weight.
4. Choose your activity level, from sedentary to very active.
5. Read your BMR and your estimated daily maintenance calories (TDEE).

The result is the calorie intake that would roughly keep your weight stable. From there you adjust up or down to reach a goal.

Activity multipliers

Your TDEE depends heavily on how active you are. The standard multipliers are:

Be honest here — overestimating activity is the most common reason a calorie plan stalls.

A worked example

Take a 30-year-old woman, 165 cm tall, weighing 65 kg, who exercises moderately.

BMR = 10 x 65 + 6.25 x 165 - 5 x 30 - 161 = 650 + 1,031.25 - 150 - 161 = 1,370

TDEE = 1,370 x 1.55 = about 2,124 calories per day to maintain her weight. To lose weight at a moderate pace she might eat around 1,600 to 1,700 (a deficit of roughly 400 to 500), and to gain she would add a similar surplus.

Using your number for a goal

Once you know your TDEE, the plan is straightforward:

• Maintain: eat at your TDEE.
• Lose weight: eat 300 to 500 below it; about 500 a day is roughly half a kilo a week.
• Gain weight or muscle: eat 250 to 500 above it, paired with strength training.

Do not drop too low, too fast — very large deficits are hard to sustain and can cost you muscle. Recheck your number as your weight changes. To track your weight status, pair this with the BMI Calculator or estimate composition with the Body Fat Calculator.

Is it free, private and accurate?

Yes to all three within reason. The Calorie Calculator is free, needs no sign-up, and does the maths locally in your browser, so your details stay on your device. It gives a solid estimate, but real needs vary by individual; treat it as a starting point and adjust based on results. For personalised medical advice, consult a professional. See more free calculators or browse all tools.