Health & Fitness
Calorie Calculator
Estimate maintenance calories, calorie deficit or surplus, macros, and projected weight change.
Result
Enter your numbers and press Calculate to see the result.
Calculating…
How your daily calories are calculated
The calculator estimates your basal metabolic rate with the Mifflin-St Jeor equation, multiplies it by an activity factor to get your maintenance calories (TDEE), then applies the daily surplus or deficit you choose for your goal. It also suggests a macro split from your editable inputs: protein grams per kilogram, fat as a percentage of calories, and carbs filling the rest.
Formulas
Maintenance (TDEE) = BMR × activity factor
Daily target = TDEE + goal offset (kcal)
Protein = protein g/kg × weight (kg) · Fat = fat% of kcal ÷ 9 · Carbs = remaining kcal ÷ 4
Activity factors
| Lifestyle | Factor |
|---|---|
| Sedentary (little exercise) | 1.2 |
| Light activity (1–3 days/week) | 1.375 |
| Moderate (3–5 days/week) | 1.55 |
| Very active (6–7 days/week) | 1.725 |
| Extra active (physical job + training) | 1.9 |
Worked example
A 30-year-old woman, 70 kg, 170 cm, moderately active (1.55): BMR ≈ 1,452 kcal, so maintenance ≈ 1,452 × 1.55 = ≈ 2,250 kcal/day. With a 500 kcal deficit the daily target is ≈ 1,750 kcal — roughly 0.45 kg (1 lb) of weight loss per week. With the default 1.8 g/kg protein and 25% fat inputs, macros are about 126 g protein, 49 g fat, and 202 g carbs.
Choosing a safe deficit or surplus
Roughly 7,700 kcal equals one kilogram of body fat (about 3,500 kcal per pound), which is why a 500 kcal daily deficit trends toward about 0.45 kg (1 lb) of loss per week. A deficit of 500–750 kcal is a common, sustainable range; cutting far more can cost muscle and is hard to maintain. For gaining, a modest surplus of 250–500 kcal supports lean growth with less fat than an aggressive bulk. Keeping protein high in either case helps preserve muscle.
Adaptive thermogenesis
Beyond the predictable drop from being smaller, prolonged dieting reduces energy expenditure further — commonly 5–15% below what the equations predict for your new weight. Thyroid output falls, NEAT falls, and movement becomes more efficient.
This is normal physiology, not a personal failing, and it is why plateaus arrive without any change in adherence. The practical responses are a diet break at maintenance for a week or two, or accepting a slower rate — not cutting further, which deepens the adaptation.
Why the number is a starting point
Every equation is a population average, and activity factors are broad buckets — real metabolism varies with genetics, NEAT (fidgeting and daily movement), sleep, and how much muscle you carry. Treat the target as a two-to-four-week experiment: track your intake and weight, and if the trend is not moving as expected, adjust by 100–200 kcal rather than assuming the formula is exact.
These figures are estimates, not medical advice. See your resting burn in detail with the BMR calculator or check your weight category with the BMI calculator.
TDEE: what it is and where the error lives
Total daily energy expenditure is everything you burn in a day, and it is what decides whether weight moves. It breaks into three parts:
| Component | Share of TDEE | What it is |
|---|---|---|
| Basal metabolic rate | ≈ 60–70% | Keeping you alive at complete rest |
| Thermic effect of food | ≈ 10% | The energy spent digesting what you eat |
| Activity and NEAT | The remainder | Deliberate exercise plus fidgeting, walking, standing |
The calculator estimates BMR with Mifflin-St Jeor and multiplies by an activity factor. That equation is the default because a 2005 systematic review in the Journal of the American Dietetic Association (Frankenfield, Roth-Yousey and Compher) compared the common predictive equations in non-obese and obese adults and found it the most reliable — consistently better than the older Harris-Benedict.
"Most reliable" is not the same as accurate. In validation against indirect calorimetry — measuring gas exchange rather than predicting it — Mifflin-St Jeor lands within ±10% of measured resting metabolic rate roughly half the time, against about a third for Harris-Benedict. Every calorie target you will ever be given carries that band.
The bigger error is upstream of the equation. Compare the spread in the activity factors: moving from moderate (1.55) to very active (1.725) raises TDEE by 11.3%, and the full range from sedentary (1.2) to extra active (1.9) is a 58% span. Picking the wrong bucket moves the answer further than the BMR equation's error does — and people reliably overestimate which bucket they are in, because a few gym sessions feel like more movement than a job that keeps you on your feet all day.
This is why the number is a starting point rather than a prescription. Maintenance calories, daily calorie needs and TDEE all name the same estimate; what makes it useful is adjusting it against two to four weeks of your own weight data, not finding a more precise formula.
Calorie deficit calculator for weight loss
A calorie deficit means average energy intake is below average energy expenditure. Selecting the weight-loss goal subtracts 500 kcal from estimated maintenance. The projection translates that fixed energy gap into an approximate weekly weight trend using 7,700 kcal per kilogram. Real loss is not perfectly linear: water, glycogen, digestion, menstrual-cycle changes, training, and metabolic adaptation can move scale weight independently of fat loss.
Calorie surplus for weight gain
A calorie surplus adds energy above estimated maintenance. The lean-gain option adds 300 kcal per day, while the larger gain setting adds 500 kcal. Resistance training, adequate protein, sleep, training history, and genetics influence how much gained weight is muscle rather than fat. A calculated surplus is a starting target, not a guarantee of a particular rate or type of weight gain.
How protein, fat, and carbohydrate macros are calculated
Protein is set from body weight in grams per kilogram. Fat receives the percentage of total calories you select, and carbohydrate receives the remaining energy. Protein and carbohydrate provide about four calories per gram, while fat provides about nine. If protein and fat settings already consume nearly all available calories, the carbohydrate result approaches zero; that is a sign to review the target and macro assumptions rather than treating the split as a required meal plan.
Metric and imperial calorie inputs
Metric mode accepts kilograms and centimeters. Imperial mode converts pounds and feet/inches internally before applying the same Mifflin-St Jeor equation. Unit choice does not change the formula or result when equivalent measurements are entered. Age and sex are formula variables because population equations estimate different average resting energy needs from those inputs; individual needs can still vary substantially.
How to adjust an estimated calorie target
- Use the estimate consistently for two to four weeks if it is appropriate for you.
- Compare weekly average body weight, not a single daily measurement.
- If the trend differs from the goal, adjust intake by a modest 100–200 kcal per day.
- Recalculate after a meaningful change in body weight or activity.
TDEE, BMR, and how they relate
BMR is what your body burns at complete rest — breathing, circulation, keeping your temperature up. TDEE is total daily energy expenditure: BMR plus everything you do on top of it. TDEE is always the larger number, and it is the one that decides whether you gain or lose weight.
TDEE = BMR × activity factor
The BMR itself comes from the Mifflin-St Jeor equation, which replaced the older Harris-Benedict formula in 1990 and is more accurate for modern body compositions:
| Equation | Formula |
|---|---|
| Men | BMR = 10 × kg + 6.25 × cm − 5 × age + 5 |
| Women | BMR = 10 × kg + 6.25 × cm − 5 × age − 161 |
The only difference between the male and female equations is that final constant — 166 kcal — which stands in for typical differences in body composition at the same height and weight.
Activity factors, and what "heavy exercise" actually means
The activity multiplier is where nearly all TDEE error comes from, because people rate themselves a category too high. These levels describe your whole week, not your best day.
| Level | Factor | What it really means |
|---|---|---|
| Sedentary | 1.2 | Desk work, no deliberate training |
| Lightly active | 1.375 | 1–3 sessions a week, or a job on your feet |
| Moderately active | 1.55 | 3–5 sessions a week of genuine effort |
| Very active | 1.725 | 6–7 hard sessions a week |
| Heavy / athlete | 1.9 | Twice-daily training, or hard physical labour on top of training |
"Heavy exercise" at 1.9 is not an enthusiastic gym habit — it describes manual work or two sessions a day. If your weight is not moving the way the numbers predict after a fortnight, the activity factor is the input to lower first.
Step-based estimates work as a cross-check: roughly 0.04 kcal per step per kilogram of body weight, so 10,000 steps at 70 kg is about 280 kcal. Watches and trackers apply their own version of this, which is why their figures and a formula rarely agree exactly.
Deficits and surpluses: setting a target
Once you have TDEE, the goal is a percentage of it rather than a flat number, so the target scales with body size.
| Goal | Adjustment | Expected rate |
|---|---|---|
| Weight loss | TDEE − 15 to 20% | 0.5–1% of body weight per week |
| Maintenance | TDEE | Stable weight |
| Weight gain | TDEE + 10 to 15% | 0.25–0.5% of body weight per week |
A kilogram of body fat holds roughly 7,700 kcal, so a 500 kcal daily deficit predicts about 0.45 kg a week. Real results run slower than the arithmetic, because TDEE falls as you get lighter and NEAT — fidgeting, posture, small movements — drops quietly during a deficit. Recalculate every 4–5 kg rather than trusting the first figure to the end.
Special cases: women, teens, and breastfeeding
- Women use the same equation with the −161 constant. Energy needs shift across the menstrual cycle by roughly 100–300 kcal, so weekly averages read better than daily ones.
- Teenagers are not covered well by adult equations, because growth itself costs energy. Adult TDEE formulas underestimate adolescent needs, and deliberate deficits during growth should involve a doctor.
- Breastfeeding adds roughly 500 kcal a day for exclusive feeding in the first six months, tapering as solids are introduced. Add it to TDEE before applying any deficit.
- Body fat percentage, if you know it, allows the Katch-McArdle equation instead, which works from lean mass and is more accurate at the extremes of body composition.
TDEE and BMI answer different questions: BMI compares your weight to your height, while TDEE tells you how much you burn. Neither says anything about the other, and a muscular person can have a high BMI and a high TDEE at once.
Food labels, portion estimates, wearable calorie readings, and activity categories all introduce error, so precision to the last calorie is not realistic. Children, adolescents, pregnant or breastfeeding people, competitive athletes, and people with medical conditions or a history of disordered eating should seek individualized advice from a qualified clinician or registered dietitian.
Calorie Calculator — frequently asked questions
What is the difference between TDEE and BMR?
BMR is what you burn at complete rest. TDEE is BMR multiplied by an activity factor, so it covers everything you do on top of resting. TDEE is always the larger number and is the one that decides weight change.
What is the TDEE formula?
TDEE = BMR x activity factor. BMR comes from Mifflin-St Jeor: 10 x kg + 6.25 x cm - 5 x age, then +5 for men or -161 for women.
What does heavy exercise mean for the activity factor?
The 1.9 multiplier describes twice-daily training or hard physical labour on top of training, not a keen gym habit. Overrating activity level is the single biggest source of TDEE error.
How big a deficit should I use to lose weight?
15 to 20% below TDEE, which works out to roughly 0.5 to 1% of body weight per week. Recalculate every 4 to 5 kg, because TDEE falls as you get lighter.
How many extra calories do I need when breastfeeding?
Roughly 500 kcal a day for exclusive breastfeeding in the first six months, tapering as solids start. Add it to TDEE before applying any deficit, and check with a health professional first.
How are my daily calories calculated?
Your BMR is estimated with the Mifflin-St Jeor equation, multiplied by an activity factor from 1.2 (sedentary) to 1.9 (very active) to get maintenance calories, then adjusted by the daily surplus or deficit you choose.
How large a deficit do I need to lose weight?
A deficit of about 500 kcal per day corresponds to roughly 0.45 kg (1 lb) of body weight per week. Moderate deficits are easier to sustain and preserve more muscle than aggressive ones.
How is the macro split calculated?
Protein uses the grams-per-kilogram value you enter (1.8 g/kg by default), fat uses the percent of calories you enter (25% by default), and carbohydrates fill the remaining calories. Protein and carbs count 4 kcal/g; fat counts 9 kcal/g.
Should I ever eat below my BMR?
Very low intakes are hard to sustain and can miss essential nutrients. These figures are general estimates, not medical advice — consult a doctor or registered dietitian before starting an aggressive diet.