Calorie/TDEE Calculator
Calculate your Total Daily Energy Expenditure (TDEE) and Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation. Get macro splits for your goals. All calculations happen locally — nothing leaves your browser.
How many calories do you need per day? Your daily requirement is your basal metabolic rate — the energy your body uses at complete rest — multiplied by an activity factor of 1.2 to 1.9. This calculator estimates BMR with the Mifflin-St Jeor equation, then applies the activity factor to give Total Daily Energy Expenditure (TDEE), the intake that holds your weight steady. Eating consistently under TDEE loses weight; eating over it gains. Every figure here is an estimate, not a prescription.
How to Use the Calorie Calculator
- Enter age, sex, height and weight — Mifflin-St Jeor needs all four. Height is in centimetres and weight in kilograms; the equation applies a different constant for men and women.
- Pick an activity level — This multiplies BMR by 1.2 to 1.9 and is the single biggest source of error. Count everything you do in a week — job, walking and training — and if you are between two levels, take the lower one.
- Choose a goal and a rate — Maintain leaves the target at TDEE. Lose or gain shifts it by 500 calories per pound per week, so 0.5 lb/week moves the target by 250 calories a day.
- Read BMR, TDEE and target — BMR is what you would burn lying still all day, TDEE is BMR plus activity, and the large number is the goal-adjusted target you would actually eat to.
- Check the macro split — The bar splits the target 30% protein, 40% carbohydrate, 30% fat, converted to grams at 4 calories per gram for protein and carbohydrate and 9 for fat.
- Copy the summary and re-test in three weeks — Copy Summary exports the numbers as text. Weigh yourself over two to three weeks and adjust the target by 200–300 calories if the trend does not match the plan.
How the Calculator Works
Everything on this page starts from the Mifflin-St Jeor equation, published in 1990 and still the prediction formula most dietitians reach for. It takes weight in kilograms, height in centimetres and age in years, and differs between men and women only in the final constant:
Men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5 Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161For a 30-year-old man at 175 cm and 75 kg: (10 × 75) + (6.25 × 175) − (5 × 30) + 5 = 750 + 1,094 − 150 + 5 = 1,699 calories. A woman with the same age, height and weight comes out at 1,533 — the 166-calorie gap reflects average differences in lean mass, not a judgement about any individual.
From BMR to TDEE
BMR only covers what your body spends staying alive. Total Daily Energy Expenditure adds movement, digestion and exercise by multiplying BMR by an activity factor. The five factors below are the standard set used with Mifflin-St Jeor, shown here against the 1,699-calorie BMR from the example above.
| Activity level | Multiplier | Typical week | TDEE at BMR 1,699 |
|---|---|---|---|
| Sedentary | 1.2 | Desk job, little or no deliberate exercise | 2,039 |
| Light | 1.375 | Light exercise 1–3 days a week | 2,336 |
| Moderate | 1.55 | Moderate exercise 3–5 days a week | 2,633 |
| Active | 1.725 | Hard exercise 6–7 days a week | 2,930 |
| Very active | 1.9 | Physical job plus daily training, or two sessions a day | 3,228 |
Goal adjustment and macros
The goal pills shift the target away from TDEE using the traditional figure of about 3,500 calories per pound of body fat, which works out at 500 calories a day per pound per week. Choosing to lose 0.5 lb a week therefore subtracts 250 calories, taking the moderate example from 2,633 to 2,383. That constant is a rule of thumb rather than a law: real weight change slows as you get lighter, because a smaller body burns less.
The macro bar then divides the target 30% protein, 40% carbohydrate and 30% fat and converts each share into grams using the standard energy values — 4 calories per gram for protein and carbohydrate, 9 for fat. At a 2,383-calorie target that is roughly 179 g protein, 238 g carbohydrate and 79 g fat. The split is a starting template; people training for strength often push protein higher and carbohydrate lower without changing the calorie total.
Why Your Real Numbers Will Differ
A prediction equation describes an average person with your height, weight, age and sex. You are not that average. Measured resting metabolic rate varies between people with identical measurements, driven by differences in lean mass, thyroid function, medication, sleep and genetics, and comparisons of the common formulas put the typical error at roughly ten percent in either direction. On a 2,600-calorie TDEE that is a spread of about 260 calories — enough to matter over a month.
The activity multiplier adds more uncertainty than the equation does. There is a large jump between each level, and most people place themselves one step too high because a few gym sessions feel more significant than the twelve hours a day spent sitting. Non-exercise movement — fidgeting, standing, walking to the shops — varies enormously between individuals and is exactly what the multiplier is trying to capture.
Treat the output as a hypothesis to test. Eat at the target for two to three weeks, weigh yourself under the same conditions several times a week, and compare weekly averages rather than single readings. If the average has not moved in the direction you wanted, change the target by 200–300 calories and repeat. After a few cycles your own data beats any equation.
These figures are informational estimates, not dietary advice or a treatment plan. Talk to a doctor or a registered dietitian before making significant changes, and especially if you are pregnant or breastfeeding, under 18, managing diabetes or another condition, or have a history of disordered eating.
Frequently Asked Questions
BMR is the energy your body would use over 24 hours doing nothing at all — running your heart, brain, kidneys and body temperature. TDEE is BMR plus everything else: digesting food, walking around, working and training. TDEE is always the larger number, typically 20% to 90% higher depending on how active you are, and it is the figure to compare your intake against.
It is the best-validated of the common prediction formulas and is generally preferred over the older Harris-Benedict equation, but it is still a population estimate. Individual results can be around ten percent off in either direction, and the error grows for people at the extremes of body composition — very muscular, very lean or very heavy. Use it as a starting point and correct it against your own weight trend.
The rate you pick is multiplied by 500 calories per day. This comes from the long-standing estimate that a pound of body fat stores roughly 3,500 calories, so a 500-calorie daily deficit predicts about a pound a week. In practice loss slows over time because a lighter body has a lower BMR, so the same deficit produces less change after a few months and the target needs recalculating.
Match it to your whole week, not your best day. Sedentary (1.2) means a desk job and no planned exercise. Light (1.375) is one to three easy sessions a week. Moderate (1.55) is three to five real training sessions. Active (1.725) is six or seven. Very active (1.9) is a physical job on top of daily training. When in doubt, pick the lower option — overestimating activity is the most common reason a plan stalls.
No. The equation runs in JavaScript on your device and nothing is sent to a server or stored on one. The only thing that travels is what you choose to share yourself: your inputs are written into the page URL so you can bookmark or send a scenario, so treat that link as personal if you paste it somewhere public.
This tool applies a balanced 30/40/30 template, which is a reasonable default for most people. If you are training with weights or in a deficit, a common approach is to fix protein first — often in the region of 1.6 to 2.2 grams per kilogram of body weight — then divide the remaining calories between carbohydrate and fat to taste. Total calories drive weight change; the split mainly affects satiety, training quality and how much muscle you keep.
Mifflin-St Jeor is built on total body weight, so it does not need one. Formulas that do use body composition, such as Katch-McArdle, calculate BMR from lean body mass and can be more accurate for very lean or very muscular people — but only if the body fat figure is itself accurate, which home scales and calipers often are not. For most users a good total-weight equation beats a good lean-mass equation fed a bad input.
Check the inputs before changing the target. Under-recorded portions, cooking oil, drinks and weekend meals are the usual culprits, and weight can stay flat for a week or two on water shifts alone. Weigh food for a few days, compare weekly average weight rather than daily readings, and confirm your activity level is not one step too high. If three consistent weeks show no trend, move the target by 200–300 calories.
Use Cases
Setting a Weekly Meal Plan
Take the goal-adjusted target, divide it across the meals you actually eat, and build a shopping list that hits the number without recalculating every evening. Re-run it after every few kilograms lost, since a lighter body has a lower TDEE.
Sizing a Lean Bulk
Pick the 0.25 lb/week rate to find the smallest surplus that still supports training — around 125 calories a day over TDEE — so weight goes up slowly enough that most of it can be muscle rather than fat.
Comparing Training and Rest Days
Run the calculator twice — once at your training-day activity level and once at sedentary — to see how far apart the two days sit, then decide whether to eat the same amount daily or cycle intake around sessions.
Checking a Diet App Against the Maths
Tracking apps rarely show how they reached your target. Work out BMR and TDEE here from the same inputs and see whether the app is using a comparable equation or quietly assuming an aggressive deficit.
Planning Food for a Long Event
Hikers, cyclists and tourers can use the very active multiplier to estimate how much energy a full day of movement costs, then work out how many days of food a pack can realistically carry.