Free Calorie Calculator
Estimate daily calories to maintain, lose or gain weight from your age, size and activity level.
Enter your age, sex, size and how active you are. The calculator estimates your resting energy with the Mifflin-St Jeor equation, multiplies it by an activity factor to find maintenance calories, then shows gentle and steady targets for losing or gaining weight.
How to use the Calorie Calculator
- Choose metric or US units and enter your own measurements.
- Read the result and the supporting numbers shown beneath it.
- Use the explanation below to see what the number means, and talk to a doctor about anything that worries you.
About the Calorie Calculator
Estimate daily calories to maintain, lose or gain weight from your age, size and activity level.
Health numbers are easier to understand when you can see how they are worked out. These calculators use published formulas and explain what the result does and does not tell you. They give general estimates and are not medical advice.
How the calculator works
It is a two-step estimate. First it works out your basal metabolic rate (BMR), the energy you burn at rest, using the Mifflin-St Jeor equation. Then it multiplies that figure by an activity factor to estimate your total daily energy expenditure (TDEE), which is the number of calories that keeps your weight steady.
Activity factors
The multiplier you choose has a large effect on the answer, so choose honestly.
| Activity level | Multiplier |
|---|---|
| Little or no exercise (desk job) | 1.2 |
| Light exercise 1 to 3 days a week | 1.375 |
| Moderate exercise 3 to 5 days a week | 1.55 |
| Hard exercise 6 to 7 days a week | 1.725 |
| Very hard exercise or a physical job | 1.9 |
Worked example
A 30-year-old woman who is 165 cm tall and weighs 60 kg has a BMR of 10 × 60 + 6.25 × 165 − 5 × 30 − 161 = 1,320 kcal. If she exercises lightly one to three days a week the multiplier is 1.375, so her maintenance figure is 1,320 × 1.375 = 1,815 kcal a day.
- Steady loss of about 0.5 kg (1 lb) a week: 1,815 − 500 = 1,315 kcal a day.
- Gentle loss of about 0.25 kg (0.5 lb) a week: 1,815 − 250 = 1,565 kcal a day.
- Gentle gain of about 0.25 kg a week: 1,815 + 250 = 2,065 kcal a day.
Why 'a pound is 3,500 calories' is only a guide
The goal figures use the common rule of thumb that about 7,700 kcal equals a kilogram of body weight (about 3,500 kcal per pound). It is a useful way to compare plans, but real results vary. Early weight changes include water, and as you lose weight your body needs fewer calories, so a fixed deficit slows down over time.
Minimums and who should not use this
Eating far below your needs can cause fatigue, muscle loss, nutrient shortfalls and other problems. The calculator flags any target below 1,200 kcal for women or 1,500 kcal for men, the minimums often quoted for unsupervised dieting.
- Do not use it if you are pregnant or breastfeeding, under 18, or managing diabetes, kidney disease or another condition that affects diet.
- Do not use it to set targets if you have, or think you may have, an eating disorder. Talk to a doctor or an eating disorder service.
- Older adults and very active people may need personal advice, because the equations are less accurate at the extremes.
Making the number useful
Track your weight for two to three weeks while eating at your estimated maintenance. If your weight is steady, the estimate fits you. If it drifts, adjust by 100 to 200 calories and watch again. Food quality, protein, sleep and strength training matter as much as the calorie total, and a registered dietitian can build a plan around your own situation.
Getting started with the Calorie Calculator
Using the calorie calculator takes a minute or two. Your entries are saved in this browser, so you can come back later and carry on.
Tips for better results
Treat the result as a starting point. Follow your weight and energy for two to three weeks, then adjust by about 100 to 200 calories. If you have a medical condition, are pregnant or are under 18, ask a doctor or dietitian first.
Use measurements you have taken recently, not remembered ones.
These tools give general estimates and are not medical advice. Check anything important with a doctor or registered dietitian.
Privacy and where your data goes
Everything you type into the calorie calculator stays on your own device. Zapxa does not receive your numbers or documents. If you clear your browser data, your saved entries will be removed, so download a PDF of anything you want to keep.
Frequently asked questions
How many calories should I eat a day?
It depends on your age, sex, size and activity. Maintenance for a lightly active 30-year-old woman who is 165 cm and 60 kg comes to about 1,815 kcal a day. Use the calculator for your own figures.
How many calories make a pound or a kilogram?
A common rule of thumb is about 3,500 kcal per pound, or about 7,700 kcal per kilogram, of body weight. It is only an approximation, and real weight change usually slows over time as the body adapts.
What is the lowest safe calorie intake?
Many guides cite 1,200 kcal a day for women and 1,500 kcal for men as a floor for unsupervised dieting. Going lower should happen only under medical supervision.
Which activity level should I choose?
Pick the option that describes a typical week, not your best week. If you are between two levels, choose the lower one, because people tend to overestimate how much they move.
Is this suitable if I have had an eating disorder?
No. If you have a history of disordered eating, or counting calories worries you, speak to a doctor or an eating disorder service rather than using a calculator.
Related Health & Age tools
- BMI Calculator — Work out your body mass index, see your adult weight category and the healthy weight range for your height.
- BMR Calculator — Estimate the calories your body burns at rest each day with the Mifflin-St Jeor and Harris-Benedict formulas.
- Ideal Weight Calculator — Compare the Devine, Robinson, Miller and Hamwi ideal body weight formulas with your healthy BMI range.
- Body Fat Calculator — Estimate body fat percentage from neck, waist and hip measurements using the U.S. Navy method.
- Pregnancy Due Date Calculator — Estimate a due date from the first day of your last period, with trimester dates and weeks pregnant.