Calorie Calculator — Daily Calories to Lose, Maintain or Gain Weight
Estimate how many calories you need each day to maintain, lose, or gain weight, then see a week-by-week projection to your goal weight that updates your calorie burn as your weight changes — with target dates, macros and safety checks.
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Projected Weight
Daily Calories by Weekly Rate
Starting targets at your current weight. Rates above about 1% of body weight a week are usually too fast to sustain.
| Goal | Daily Calories | Change vs Maintenance | % of Body Weight / Week | Check |
|---|
Macros for Your Target
Protein set by body weight to help preserve muscle, fat at 25–30% of calories, carbohydrate making up the rest.
| Macronutrient | Grams / Day | Calories | % of Calories | Basis |
|---|
This calculator is a general estimate for adults. Calorie needs can require individualized assessment during pregnancy or breastfeeding, for people under 18, for competitive athletes, or when a medical condition or medication affects nutrition or energy needs. If any of these apply, consider guidance from a qualified healthcare professional.
How this calculator works
This calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR), then multiplies it by an activity factor to estimate total daily energy expenditure — your maintenance calories.
BMR (men) = 10W + 6.25H − 5A + 5 · BMR (women) = 10W + 6.25H − 5A − 161 — W = weight in kg · H = height in cm · A = age in years
The projection: your daily target stays fixed, but each week the calculator recalculates your maintenance calories at your new, lower (or higher) weight. The gap shrinks, so progress slows over time — which is closer to real life than assuming the same weekly loss forever. It doesn't model extra metabolic adaptation, water-weight swings or changes in activity, so treat dates as estimates. For a research-grade model, see the NIH Body Weight Planner, based on work by Kevin Hall and colleagues.
By Suhaib Hassan · Reviewed 28 September 2026 against the original equations and NIH guidance · How CalculatePilot verifies formulas →
Using this to lose or gain weight
A deficit of roughly 500–550 calories a day tends to produce about 0.5 kg of weight loss per week at first, since one kilogram of body fat corresponds to roughly 7,700 calories (0.5 × 7,700 ÷ 7 = 550 a day). The same logic in reverse applies to weight gain.
Why calorie needs vary so much between people
Two people with identical height, weight, and age can still have meaningfully different calorie needs due to differences in muscle mass, genetics, and daily activity outside of formal exercise (often called NEAT — non-exercise activity thermogenesis).
This calculator provides a solid starting estimate, but the most reliable way to find your true maintenance calories is to track your actual weight trend over 2-3 weeks at a consistent intake and adjust from there based on real results. If you're specifically aiming to lose weight, the Weight Loss Calorie Calculator builds a target deficit on top of this number.
A worked example
A 35-year-old man, 80 kg, 178 cm, lightly active: BMR works out to 10 × 80 + 6.25 × 178 − 5 × 35 + 5 = about 1,743 calories, and multiplying by the 1.375 activity factor gives a maintenance level of about 2,396 calories/day.
For illustration, a calorie target can be set below or above maintenance, but the appropriate size of that change depends on the person and goal. The simple energy-balance model used here should not be treated as a guarantee of a particular weekly weight change.
Why calorie needs change over time
As you lose or gain weight, your calorie needs shift too — a smaller body generally burns fewer calories at rest, and a larger body burns more. This is why weight loss often slows over time even at a consistent deficit, and why recalculating every few weeks (rather than once) tends to produce more accurate ongoing targets.
Body composition can affect energy expenditure, but the effect of changing muscle mass on total calorie needs varies between people. Medical information, not medical advice: talk to a doctor or registered dietitian before a substantial dietary change, especially if you're pregnant, under 18 or managing a health condition.
Sources
- Mifflin et al. (1990), A new predictive equation for resting energy expenditure — PubMed
- NIH / NIDDK Body Weight Planner
- Mayo Clinic Calorie Calculator
- Jäger R, et al. International Society of Sports Nutrition position stand: protein and exercise. J Int Soc Sports Nutr 2017;14:20.
Read the guides: How many calories should I eat a day? · How to calculate your TDEE · How many calories to eat to lose 1 pound a week
Activity levels and the multipliers behind them
Your maintenance calories are your BMR multiplied by an activity factor. The calculator uses the five factors below. The last column shows the result for the 35-year-old man in the worked example (80 kg, 178 cm, BMR about 1,743 calories).
| Activity level | Multiplier | What it looks like | Maintenance for the example |
|---|---|---|---|
| Sedentary | 1.2 | Desk job, little or no exercise | 2,091 |
| Light activity | 1.375 | Exercise 1–3 days a week | 2,396 |
| Moderate activity | 1.55 | Exercise 3–5 days a week | 2,701 |
| Very active | 1.725 | Hard exercise 6–7 days a week | 3,006 |
| Extremely active | 1.9 | Physical job plus training | 3,311 |
Most people choose a level that is too high. If you are unsure between two levels, pick the lower one, track your weight for two to three weeks and adjust.
Mifflin-St Jeor vs Harris-Benedict: how much do the results differ?
Calorie calculators use different BMR equations, so the same person can see different numbers on different sites. The 1919 Harris-Benedict equation, which some calculators still use, tends to give a higher BMR than Mifflin-St Jeor for many adults. Both are estimates.
| Person | Mifflin-St Jeor BMR | Harris-Benedict BMR | Maintenance at 1.375 (Mifflin / Harris-Benedict) |
|---|---|---|---|
| Man, 35, 80 kg, 178 cm | 1,743 | 1,821 | 2,396 / 2,504 |
| Woman, 35, 65 kg, 165 cm | 1,345 | 1,418 | 1,850 / 1,950 |
The gap is about 100 calories a day in these examples. That is small next to the error from picking the wrong activity level, which can move the result by 300 calories or more.
Calorie deficit and surplus: what each daily gap does
One kilogram of body weight change is treated as roughly 7,700 calories (about 3,500 per pound). Dividing a daily gap by that figure gives the expected weekly change. The target column uses the example man's maintenance of 2,396.
| Daily deficit | Weekly change | Daily target for the example |
|---|---|---|
| 250 calories | about 0.23 kg (0.5 lb) | 2,146 |
| 500 calories | about 0.45 kg (1 lb) | 1,896 |
| 750 calories | about 0.68 kg (1.5 lb) | 1,646 |
| 1,000 calories | about 0.91 kg (2 lb) | 1,396 |
A surplus works the same way in reverse: adding 300 calories to maintenance suggests about 0.27 kg (0.6 lb) of gain a week, though some of it will be water, and not all of it will be fat. The calculator's projection slows over time because maintenance falls as you lose weight. For a gap above 750 calories, talk to a doctor or dietitian first.
Net calories: food eaten minus exercise burned
Net calories means calories eaten minus calories burned in exercise. If you eat 2,000 calories and burn 350 in a run, your net is 1,650. This calculator already includes exercise in the activity factor, so do not subtract workouts a second time from the target it gives you. Subtract exercise only if you chose the sedentary level and track workouts separately.
Typical daily calorie ranges
The US Dietary Guidelines estimate that adult women need roughly 1,600 to 2,400 calories a day and adult men roughly 2,000 to 3,000, depending on age and activity. Your own number can sit outside those ranges, especially if you are very tall, very small, pregnant or training hard.
How low is too low?
Many dietitians use about 1,200 calories a day for women and 1,500 for men as a floor that should not be passed without medical supervision. Eating that little can make it hard to get enough protein, iron and other nutrients. If your target falls below those figures, choose a slower rate or a longer timeline.
Counting the calories in your food
This calculator tells you how many calories to aim for. It does not look up the calories in individual foods. To use your target, log what you eat in a food diary or a nutrition label database for two weeks, compare the average with your target, and adjust portions. For drinks, see our guides on calories in beer, wine and spirits and calories in mixed drinks.
Related guides
More sources
Frequently asked questions
How accurate is this calorie estimate?
It is a predictive estimate, not a direct measurement of energy expenditure. Individual metabolism and activity vary, so use it as a starting point and compare it with your real-world trend over several weeks.
Why does activity level matter so much?
Activity level changes the estimate because everyday movement and exercise contribute to total energy expenditure. The size of that difference varies substantially between people.
Why am I not losing weight at my calculated deficit?
Common causes include underestimating portion sizes, overestimating exercise calories burned, or a maintenance calorie level that's actually different from the formula's estimate — tracking actual results over a few weeks helps calibrate.
Is it safe to eat below my calculated deficit?
There is no single calorie floor that is appropriate for every adult. Very-low-calorie diets can create nutritional and other health risks and should only be undertaken with appropriate clinical supervision.
Should I recalculate my calorie needs as I lose weight?
Yes — as body weight changes, so does your BMR and total calorie needs, so recalculating every few weeks during an active weight loss or gain phase keeps your target accurate.
Is a 500-calorie deficit always the right target?
A fixed 500-calorie deficit is not appropriate for everyone. The size of a deficit should be individualized rather than treated as a guaranteed weekly weight-loss formula.
Why does my projected weight loss slow down over time?
Because energy needs can change as body weight, body composition and activity change. The projection is a simplified model and should be compared with real-world trends rather than treated as a guaranteed forecast.
What is a calorie calculator and what does it tell me?
A calorie calculator estimates how many calories you burn in a day (maintenance calories) from your sex, age, height, weight and activity level. It then adjusts that number up or down for your weight goal, so you get a daily calorie target.
How do I calculate a calorie deficit?
Subtract your target intake from your maintenance calories. For a man with maintenance of 2,396 calories who eats 1,896, the deficit is 500 calories a day. At about 7,700 calories per kilogram, that is roughly 0.45 kg (1 lb) a week.
How many calories should I cut to lose weight?
A common range is 250 to 750 calories a day below maintenance, which is about 0.2 to 0.7 kg (0.5 to 1.5 lb) a week. A larger cut needs a doctor or dietitian's advice, and your target should not fall under the minimum your health professional recommends.
What is a calorie surplus and how big should it be?
A calorie surplus is eating more than your maintenance calories. For gradual weight gain, 250 to 500 calories a day above maintenance is typical. Adding 300 calories suggests about 0.27 kg (0.6 lb) a week.
What are net calories?
Net calories are calories eaten minus calories burned through exercise. If you eat 2,000 and burn 350 exercising, your net is 1,650. This calculator builds exercise into the activity factor, so do not subtract workouts again.
Which activity level should I choose?
Pick the lowest level that honestly fits your week: 1.2 for little or no exercise, 1.375 for 1–3 workouts, 1.55 for 3–5, 1.725 for 6–7 and 1.9 for a physical job plus training. If unsure, choose lower and adjust after two to three weeks.
Why does another calorie calculator give me a different number?
Calculators use different equations. This one uses Mifflin-St Jeor. Others use the 1919 Harris-Benedict equation or equations from the Institute of Medicine. For the example man the maintenance figure is 2,396 with Mifflin-St Jeor and 2,504 with Harris-Benedict, about 100 calories apart.
How many calories do men and women need a day?
The US Dietary Guidelines give roughly 1,600 to 2,400 calories for adult women and 2,000 to 3,000 for adult men, depending on age and activity. Use the calculator for a figure based on your own height and weight.
Is 1,200 calories a day enough?
Many dietitians treat 1,200 for women and 1,500 for men as a floor not to pass without medical supervision. Below that it is harder to get enough nutrients, so talk to a doctor or dietitian first.
Can I use this calculator to count the calories in my food?
No. It sets a daily target. To count food calories, log what you eat in a food diary or use nutrition labels, then compare your average intake with the target.
Next Steps
Plan the details of your diet and track progress.