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Calorie Calculator.
How many calories your body burns in a day, and the daily target for the goal you pick — using the same formulas dietitians start from.
Estimates for healthy adults, not a diagnosis or medical advice. Formulas like these are population averages and can be off for athletes, older adults, pregnant people and anyone with a medical condition. Talk to a clinician before changing your diet or training. Nothing you type here leaves your browser. Terms.
Every goal, side by side
A starting macro split
30% protein, 40% carbohydrate, 30% fat at your target. Protein and carbs are 4 kcal per gram, fat is 9. Adjust to taste; the calories are what matter most.
Guide
How to use the Calorie Calculator
This calculator estimates how many calories your body burns in a day, then adjusts that number for whether you want to hold steady, lose weight or gain it. The answer is only as good as your honesty about one field: activity level.
- Choose your Units: US (ft, in, lb) or Metric (cm, kg).
- Enter your Age in years. The formulas assume you are an adult.
- Choose your Sex. Men and women of the same size and age burn different amounts at rest.
- Enter your Height and Weight: feet, inches and pounds in US units, centimeters and kilograms in metric. Use your current weight, not your goal.
- Pick your Activity level. Each option has a one-line description. Choose the one that honestly describes your average week, job included, not just your workouts. Most desk workers who exercise a few times a week are lightly or moderately active.
- Leave the Formula set to Mifflin-St Jeor unless you have a reason to change it. Katch-McArdle needs the Body fat field filled in, so use it only if you have a decent measurement.
- Pick your Goal: maintain, lose ½, 1 or 2 pounds a week, or gain ½ or 1 pound a week.
- Read the results: your daily target, your BMR, your maintenance calories, a table of every goal, and a macro split for your target.
How the math works
There are two layers. The first is your basal metabolic rate, or BMR: the calories your body burns just keeping you alive, lying still, not digesting anything. It depends on your size (weight and height), your age, and sex.
The second layer is everything you actually do. BMR times an activity factor gives your total daily energy expenditure, or TDEE, also called maintenance calories. Eat about that much and your weight holds steady.
Goals are a fixed daily surplus or deficit from maintenance. A pound of body fat stores roughly 3,500 calories, so a 500-calorie daily deficit works out to about a pound a week, and 1,000 to about two. Gaining uses smaller steps, because large surpluses mostly add fat.
The macro split is 30 percent protein, 40 percent carbohydrate, 30 percent fat, at 4 calories per gram for protein and carbohydrate and 9 for fat. It is a default, not a prescription.
The formula
Mifflin-St Jeor BMR (men) = 10 × W + 6.25 × H − 5 × A + 5
Mifflin-St Jeor BMR (women) = 10 × W + 6.25 × H − 5 × A − 161
Maintenance (TDEE) = BMR × M
Goal calories = TDEE − 250, − 500 or − 1,000 to lose ½, 1 or 2 lb a week; TDEE + 250 or + 500 to gain ½ or 1 lb a week
W is weight in kilograms, H is height in centimeters, A is age in years, and M is the activity multiplier: sedentary 1.2, lightly active 1.375, moderately active 1.55, very active 1.725, extra active 1.9. Katch-McArdle uses 370 + 21.6 × lean mass in kilograms.
Worked example
Take a 30-year-old man, 5 feet 11 inches, 185 pounds, moderately active, using Mifflin-St Jeor. In metric: 71 inches × 2.54 = 180.34 cm, and 185 pounds × 0.45359237 = 83.91 kg.
BMR = 10 × 83.91 + 6.25 × 180.34 − 5 × 30 + 5 = 839.1 + 1,127.1 − 150 + 5 = 1,821 calories, what he burns doing nothing at all. Maintenance = 1,821 × 1.55 = 2,823 calories a day; activity adds about 1,000 calories to his resting burn.
| Goal | Adjustment | Calories per day |
|---|---|---|
| Lose 2 lb a week | −1,000 | 1,823 |
| Lose 1 lb a week | −500 | 2,323 |
| Lose ½ lb a week | −250 | 2,573 |
| Maintain | 0 | 2,823 |
| Gain ½ lb a week | +250 | 3,073 |
| Gain 1 lb a week | +500 | 3,323 |
At the 2,323-calorie target, the 30/40/30 split works out to about 174 g of protein, 232 g of carbohydrate and 77 g of fat.
Switch the Formula to Revised Harris-Benedict and the same man gets a BMR of 1,908, about 86 calories or 4.7 percent higher, pushing maintenance to 2,957. That disagreement is normal. These formulas were fit to groups, and any one person can sit a few percent off the line.
What moves the result most
- Activity level. By far the biggest lever. The same 1,821 BMR becomes 2,186 at sedentary and 3,460 at extra active, a spread of more than 1,200 calories. Picking "very active" because you train four times a week, when you otherwise sit all day, can overstate your burn by hundreds of calories.
- Weight. Each 10 pounds adds about 45 calories to BMR, more after the multiplier. As you lose weight your target drops, so rerun the numbers every 10 pounds.
- Age. Every decade shaves 50 calories off BMR.
- Sex. The male and female versions differ by 166 calories at rest for the same size and age.
How to read the result
Use the target as a two-week experiment, not a rule. Eat close to it, weigh yourself a few mornings a week, and compare the trend to what the goal predicts. If you aimed to lose a pound a week and lost nothing, your real maintenance is lower than the estimate; trim 100 to 200 calories and try again. Losing faster than planned, add some back.
Pay attention to the safety note. If a target falls under 1,200 calories for women or 1,500 for men, the calculator flags it, because it gets hard to meet basic nutrition needs below those levels. Pick a slower goal. Aggressive deficits also cost muscle, so most people do better at a half pound to a pound a week.
The Body Fat Calculator estimates lean mass from a tape measure, which is what Katch-McArdle wants. The BMI Calculator gives a quicker, rougher read.
These results are estimates for healthy adults and are not a diagnosis or a medical plan. If you have a medical condition, are pregnant or breastfeeding, are an athlete, or are under 18, your needs can differ a lot from what these formulas predict, and you should talk to a clinician or a registered dietitian first.
What this calculator doesn't do
It does not measure anything. It predicts your burn from a formula built on population averages, and individual metabolisms vary by a few hundred calories either way. It does not account for how your body adapts to a long deficit, for medications that affect appetite or metabolism, or for fat loss versus muscle loss.
It also does not tell you what to eat. The macro split is one default among many and says nothing about food quality, fiber or micronutrients.
Frequently asked questions
How many calories should I eat a day to lose weight?
Start from your maintenance calories, which is your BMR multiplied by an activity factor, and subtract 500 a day to lose about a pound a week or 1,000 to lose about two. A moderately active 30-year-old man at 5 feet 11 inches and 185 pounds maintains at about 2,823 calories, so a pound a week means roughly 2,323.
What is BMR and how is it different from maintenance calories?
BMR, or basal metabolic rate, is what your body burns at complete rest. Maintenance calories, also called TDEE, multiply BMR by an activity factor from 1.2 for sedentary to 1.9 for extra active to cover everything you actually do in a day. In the example above, a 1,821 BMR becomes 2,823 maintenance at moderate activity.
Which calorie formula is most accurate?
Mifflin-St Jeor is the usual default and performs well for most adults, which is why this calculator starts there. Revised Harris-Benedict is an older formula that typically lands within a few percent of it. Katch-McArdle uses lean body mass and is only as good as the body fat percentage you give it.
How do I choose the right activity level?
Describe your whole week, not just your workouts. A desk job plus three or four gym sessions is usually lightly or moderately active, not very active. Overstating activity is the most common reason a calorie target fails to produce results.
Why does a 500-calorie deficit equal a pound a week?
A pound of body fat stores roughly 3,500 calories, and 500 × 7 days = 3,500. It is an approximation that holds reasonably well at first and gets looser as your body adapts and your weight changes, so recheck your numbers every 10 pounds or so.
Is it safe to eat 1,200 calories a day?
Below about 1,200 calories for women or 1,500 for men it becomes difficult to get enough protein, vitamins and minerals, which is why the calculator flags targets under those levels. If your goal pushes you there, pick a slower rate of loss, and talk to a clinician before going lower.
How many calories do I need to gain weight or build muscle?
Add 250 calories a day above maintenance for about half a pound a week or 500 for about a pound. Larger surpluses mostly add fat rather than muscle, so most people do better with the smaller step plus adequate protein and resistance training.
Estimates for healthy adults, not a diagnosis or medical advice. Formulas like these are population averages and can be off for athletes, older adults, pregnant people and anyone with a medical condition. Talk to a clinician before changing your diet or training. Nothing you type here leaves your browser. See the terms of use.
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