Macro Calculator
A macro calculator turns a calorie target into grams of protein, carbohydrate and fat. A moderately active 35-year-old…
Calorie Calculator
A calorie calculator estimates how many calories you burn in a day and how many to eat to reach your goal. A moderately active 35-year-old man who weighs 80 kg (176 lb) and is 180 cm (5 ft 11 in) tall burns about 2,720 kcal a day, so around 2,170 kcal a day would lose roughly 0.5 kg a week.
How to use this TDEE calculator
- Enter your details. Choose your sex, then enter your age, weight and height in metric or imperial units.
- Pick an honest activity level. Most people overestimate activity. If you have a desk job and train three times a week, choose lightly or moderately active, not very active.
- Choose a goal. Select how fast you want to lose or gain weight. Slower rates are easier to stick to and preserve more muscle.
- Track and adjust. Eat close to the target for 2–3 weeks, weigh yourself at the same time each week, and adjust by 100–200 kcal if needed.
BMR, TDEE and maintenance calories explained
- BMR (basal metabolic rate) is the energy your body uses at complete rest to breathe, circulate blood and keep organs working. For most people it is 60–70% of daily burn.
- TDEE (total daily energy expenditure) is BMR plus the energy used by movement, exercise and digesting food.
- Maintenance calories are the same as your TDEE: eat this much on average and your weight stays stable.
The NHS uses rough guides of around 2,500 kcal a day for men and 2,000 kcal for women, but your own figure can be several hundred calories higher or lower depending on your size, age and activity. That is why a personal estimate is more useful than a general one.
The Mifflin–St Jeor equation behind this BMR calculator
This calculator uses the Mifflin–St Jeor equation, published in 1990 and found in a 2005 systematic review to be the most accurate of the common equations for healthy adults:
- Men:
BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 - Women:
BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Worked example: a 35-year-old man, 80 kg, 180 cm. BMR = 800 + 1,125 − 175 + 5 = 1,755 kcal. Multiply by 1.55 for moderate activity and his TDEE is about 2,720 kcal a day.
Even the best equation can be off by around 10% for an individual. Treat the result as a starting point and let your weekly weigh-ins fine-tune it.
Activity multipliers
TDEE is BMR multiplied by an activity factor. For a 35-year-old woman who weighs 65 kg and is 165 cm tall (BMR about 1,350 kcal):
| Activity level | Multiplier | Maintenance calories |
|---|---|---|
| Sedentary | 1.2 | 1,610 kcal |
| Lightly active | 1.375 | 1,850 kcal |
| Moderately active | 1.55 | 2,090 kcal |
| Very active | 1.725 | 2,320 kcal |
| Extremely active | 1.9 | 2,560 kcal |
The gap between sedentary and very active is over 700 kcal a day, so picking the right level matters more than any other input.
Using it as a calorie deficit calculator
To lose weight you need to eat less than you burn. A common rule of thumb is that about 7,700 kcal equals 1 kg of body fat (3,500 kcal per pound), so a deficit of 550 kcal a day works out to roughly 0.5 kg a week. Real weight loss tends to slow over time because a smaller body burns fewer calories, which is why you should recalculate every 5 kg or so.
- 0.25–0.5 kg a week is sustainable for most people and helps keep muscle.
- 1 kg a week needs a large deficit and is usually only appropriate for people with a lot of weight to lose, ideally with medical support.
- Many health bodies advise not going below about 1,200 kcal a day for women or 1,500 kcal for men without supervision. The calculator flags any target below these levels.
Who should not rely on a maintenance calories calculator
Equations are built from data on healthy adults, so they are less reliable if you are pregnant or breastfeeding, under 18, very muscular, recovering from illness, or living with a condition such as thyroid disease or diabetes. Anyone with a history of disordered eating should plan changes with a doctor or registered dietitian rather than a calculator.
Calorie calculator FAQs
How many calories should I eat to lose weight?
Start about 500–550 kcal below your maintenance calories for roughly 0.5 kg (1 lb) a week. For a moderately active 35-year-old woman of 65 kg and 165 cm that is about 1,540 kcal a day.
What is the difference between BMR and TDEE?
BMR is what you burn at complete rest. TDEE adds everything else: walking, exercise, work and digesting food. You should eat based on TDEE, not BMR.
Should I eat back the calories I burn exercising?
No, if you chose an activity level that already includes your exercise. Fitness trackers also tend to overestimate calories burned, so adding them on top often cancels out the deficit.
Why has my weight loss stopped?
As you lose weight, your maintenance calories fall. Recalculate with your new weight, check your portion sizes, and give it two or three weeks before changing anything, as water weight can hide fat loss.
Is this calorie calculator accurate?
It uses the most validated everyday equation, but any equation can be about 10% out for an individual. Your weekly weigh-ins are the real test: if your weight does not change as expected, adjust by 100–200 kcal.
Sources and methodology
BMR uses the Mifflin–St Jeor equation. TDEE multiplies BMR by standard activity factors (1.2, 1.375, 1.55, 1.725, 1.9). Goals add or subtract a fixed daily amount based on about 7,700 kcal per kg of body weight change. Results are rounded to the nearest 10 kcal. Targets below 1,200 kcal (women) or 1,500 kcal (men) are flagged. All example figures were produced by this calculator.
- Mifflin MD et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr
- Frankenfield D et al. (2005). Comparison of predictive equations for resting metabolic rate. J Am Diet Assoc
- NHS: Understanding calories
- NIDDK: Body Weight Planner
- Harvard Health Publishing: Calorie counting made easy
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