Calorie calculator

Your everyday energy number, in stone or kilos. It never goes below a safe floor and it will not nag you. For adults 18 and over.

To stay about where you are

1,940

kcal a day

Resting energy1,410
Everyday movement+ 530
NHS guide for women2,000

That is roughly what your body uses on a normal day. It is an estimate, so use it as a starting point and see how you feel.

Your result

What your number means

It is an estimate of the energy your body uses on a normal day. Bodies vary, so think of it as a starting point, then see how you feel.

Resting energyWhat you would use lying still all day: breathing, thinking, keeping warm. This is the biggest part.
Everyday movementWalking to the bus, the school run, the gym, gardening. Your activity level sets this.
The NHS guideThe NHS uses 2,000 kcal a day for women and 2,500 kcal for men as a rough average. Yours may be higher or lower.

The working

How we work it out

We use the Mifflin St Jeor equation, which researchers found to be among the most accurate for most adults.

Resting energy = 10 × kg + 6.25 × cm − 5 × age, then −161 for women or +5 for men

Then we multiply by your activity level, from 1.2 for mostly sitting to 1.9 for a physical job plus training. For a 38 year old woman who is 11 st 0 lb (69.9 kg) and 5 ft 7 in (170 cm): 699 + 1,063 − 190 − 161 = 1,411 kcal at rest, and × 1.375 for a bit active = about 1,940 kcal a day.

Our safety rules

Floors we never go below

Your resting energyA loss target never dips under what your body needs at rest.
1,200 kcal, or 1,500 for menVery low calorie diets need medical supervision, so we stop here.
No loss targets for someNot for under 18s, in pregnancy, while breastfeeding, or with a BMI under 18.5.

Questions

Common questions

Why is my number different from an app?

Apps use different equations and guess your activity differently. A difference of 100 or 200 kcal is normal. None of them can measure you exactly.

How fast is it safe to lose weight?

The NHS says a cut of about 600 kcal a day is a common way to lose 0.5 to 1 kg a week. Slower is fine. Faster is rarely kinder.

Do I need more in pregnancy?

The NHS says you do not need extra calories in the first 6 months. In the last 3 months, about 200 kcal a day extra. Your midwife can help with the rest.

Can I use this for my teenager?

No. Children and teenagers are still growing, so adult equations do not fit. A GP, school nurse or health visitor can help.

Sources

Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.

When to talk to someone

Talk to your GP if your weight has changed a lot without trying, or if you have a health condition that affects what you eat. If food or your body feels hard to think about, Beat has a free helpline on 0808 801 0677. A pharmacist can help with quick questions too.