Calorie calculator
Enter your age, height, weight and activity level to estimate your maintenance calories (TDEE) and a daily target for losing, keeping or gaining weight.
Filled in with example values. Replace them with yours.
Your daily target
- Maintenance
- 2,730 kcal
- At rest (BMR)
- 1,760 kcal
- Protein / carbs / fat
- 156 / 243 / 65 g
- Expected change
- −0.5 kg a week
Formulas like this are typically within about ±10 % for most people. Treat the number as a start and check it against your weight trend.
Work out your protein needs →| Level | Factor | Maintenance |
|---|---|---|
| Mostly sitting | × 1.2 | 2,110 kcal |
| Lightly active | × 1.375 | 2,420 kcal |
| Moderately active | × 1.55 | 2,730 kcal |
| Very active | × 1.725 | 3,040 kcal |
| Extremely active | × 1.9 | 3,340 kcal |
How the calculator works
It takes three steps, and you can see each one next to the result.
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Resting energy (BMR). The calculator uses the Mifflin-St Jeor equation, derived from 498 healthy adults whose resting energy was measured (Mifflin 1990):
BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 (men) or − 161 (women)
If you choose “Not specified”, it uses the mean of both constants, −78.
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Maintenance. Resting energy times an activity factor, from 1.2 for a mostly sitting day to 1.9 for hard daily training plus a physical job. For a 30-year-old man of 180 cm and 78 kg, that is 1,760 × 1.55 = 2,728, shown as 2,730 kcal.
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Your target. Maintenance minus (to lose) or plus (to gain) the energy that your chosen pace needs, rounded to 10 kcal.
A systematic review compared the common equations and found Mifflin-St Jeor within 10 % of measured resting energy for more people than any other (Frankenfield 2005). It also warns about noteworthy errors for individuals, which is the honest limit of every calculator of this kind.
BMR vs. TDEE: what is the difference?
Your BMR (basal metabolic rate) is the energy your body burns at complete rest: breathing, circulation, keeping warm and running your organs. It is the first number the calculator works out. Your TDEE (total daily energy expenditure) is your BMR plus everything else you do in a day: walking, working, training and digesting food. It decides whether your weight goes up, down or stays put, and this page calls it maintenance. In short, BMR times your activity factor gives your TDEE, and your daily target is your TDEE minus or plus the energy for the pace you chose.
Which activity level am I?
Count the training you do in a normal week and what your day looks like around it. The five levels are listed with an example and their factor, and the table next to the result shows what each one means in kcal for you.
Most people choose too high. An hour in the gym burns a modest amount, and the other 23 hours matter as much. If you hesitate between two levels, take the lower one. “Moderately active” suits someone who trains three to five times a week. The top level is for people who train hard every day and also work on their feet or lift for a living.
How big a deficit or surplus?
One kilogram of body weight is often put at about 7,700 kcal. That gives the pace options:
- Losing: 0.25, 0.5 (recommended), 0.75 or 1.0 kg a week, which is a deficit of about 275 to 1,100 kcal a day.
- Gaining: 0.1, 0.25 (recommended) or 0.5 kg a week, a surplus of about 110 to 550 kcal a day.
Slow and steady wins for people who lift. A review of contest preparation advises losing about 0.5 to 1 % of body weight per week to keep as much muscle as possible (Helms 2014). For a 78 kg person that is 0.4 to 0.8 kg. A faster pace is possible, but you pay for it in muscle, energy and the odds of sticking with it.
The 7,700 kcal rule is an average, not a law. The energy in a kilogram you lose depends on how much of it is fat and how much is lean mass, and the old rule overestimates the deficit needed for people who are already lean (Hall 2008). You also burn less as you get lighter. Both are why the real result drifts from the plan.
The calorie floor
The calculator never sets a losing day below 1,500 kcal for men and 1,200 kcal for women or anyone who did not give a sex. Below that it is hard to get enough protein, vitamins and minerals. When the floor applies, the calculator says so and shows the real weekly rate you get, which is slower than the pace you picked.
Under 18, the calculator shows maintenance only and no deficit. You are still growing, and if you want to lose weight you should plan it with a doctor.
Macros: protein, fat and carbs
The macros follow the same rules as the app:
- Protein: 1.8 g per kg of body weight, and 2.0 g per kg when you lose weight. Training while eating less is when protein protects your muscle most.
- Fat: 27 % of the day’s calories.
- Carbs: everything that is left.
For a closer look at protein, open the protein calculator from the link under the result. It takes your weight with it.
Why a formula is only a start
Two people with the same age, height and weight can differ by several hundred kcal a day. Genes, muscle mass, daily steps and earlier dieting all play a part, and no equation sees them. The best data you have is your own: weigh yourself most mornings, look at the weekly average and compare it with the pace you wanted. If you lose faster than planned, eat a little more. If nothing changes for two or three weeks, eat a little less or move a little more.
Calories in Muscla
Muscla starts with the same math, using a factor of 1.5 for people who train regularly, then keeps going where a calculator stops. Once a week it compares your target with your weight trend in the food tab and tells you if the number should change. You log your meals by scan or by hand, and the day target and macros sit next to them.
Coming to the App Store. Free to start.
Questions
What are maintenance calories?
Maintenance calories are the energy you burn in a day at your current weight: resting energy, movement, exercise and digesting food. Eat that much and your weight stays roughly stable. Eat less and you lose weight, eat more and you gain.
Is a calorie calculator accurate?
It is a good estimate, not a measurement. A systematic review found the Mifflin-St Jeor equation within 10 % of measured resting energy in more people than the other common equations, but with real errors for individuals (Frankenfield 2005). The activity factor adds more uncertainty on top. That is why a weekly check against your weight trend matters more than the first number.
How many calories should I eat to lose weight?
Eat below maintenance by a moderate amount. A deficit of about 550 kcal a day gives roughly 0.5 kg (1.1 lb) a week by the usual rule of thumb, which suits most people. Going faster costs more muscle and is harder to keep up. Keep the day at 1,500 kcal or more for men and 1,200 kcal or more for women.
How big a calorie deficit is sensible?
A moderate one. The calculator offers paces from 0.25 to 1 kg (0.55 to 2.2 lb) a week, which is a deficit of about 275 to 1,100 kcal a day, and recommends 0.5 kg a week, about 550 kcal a day. Smaller deficits are easier to keep up and protect muscle better. The target never drops below 1,500 kcal for men and 1,200 kcal for women or anyone who did not give a sex, and under 18 there is no deficit.
Why does my weight loss slow down?
You weigh less, so you burn less, and a fixed target becomes a smaller deficit every week. The 7,700 kcal per kg rule is also only a rough average and changes with body fat and how much lean mass you lose (Hall 2008). Run the calculator again with your new weight every few kilos.
Which activity level should I pick?
When you are between two levels, pick the lower one. Most people overestimate how much they move outside their workouts, and one hour of training barely changes a day spent sitting. Then let the scale decide: if your weight does not move the way the calculator predicts, adjust by one level.
How many calories does Muscla use?
Muscla uses the same formulas and floors as this page. For people who train regularly it starts with a factor of 1.5 on the resting energy, and every week it checks your target against your weight trend in the food tab, then tells you if the number needs to move.
Sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition. 1990;51(2):241-247.
- Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association. 2005;105(5):775-789.
- Hall KD. What is the required energy deficit per unit weight loss? International Journal of Obesity. 2008;32(3):573-576.
- Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition. 2014;11:20.