Calorie Calculator
This calorie calculator estimates how many calories you need a day to maintain, lose, or gain weight. Enter your age, sex, height, weight, and activity level, and you'll get your maintenance calories plus clear targets for each goal, worked out with the Mifflin-St Jeor formula. It's the number to aim for, whether you're cutting, bulking, or holding steady.
- Maintenance calories
- Weight-loss targets
- Mifflin-St Jeor
- Activity levels
- Metric or imperial
Last updated June 16, 2026 Estimates only, not medical advice Reviewed by the Calcowa team
Enter your age, height, and weight above 0.
For adults. This is a screening estimate, not medical or dietary advice.
These are estimates, not medical or dietary advice. Don't drop below about 1,200 calories (women) or 1,500 (men) without professional guidance.
Calorie targets for every goal
Each weight-loss row is your maintenance number minus a daily deficit; each gain row adds a surplus. About 3,500 calories is a pound, so 500 a day trends toward a pound a week.
| Goal | Calories a day | Rate |
|---|
How many calories should I eat?
The honest answer is that it depends on you. Your body burns a baseline amount just staying alive, called your basal metabolic rate, and more on top for moving around. Add those together and you get the calories that hold your weight steady, your maintenance level. Eat below it and you lose weight; eat above it and you gain. That's the whole model. This calculator works out all three from a few numbers, so instead of guessing you've got a target to aim at.
How are daily calories calculated?
The calculator uses the Mifflin-St Jeor equation, the current standard. Here's how it runs for a 30-year-old man, 178 cm and 73 kg, who's moderately active:
- 1
Find your BMRMifflin-St Jeor: 10 × kg + 6.25 × cm − 5 × age + 5 for men (− 161 for women). That gives about 1,692 calories.
- 2
Multiply by activityModerately active uses a factor of 1.55, so 1,692 × 1.55 is about 2,623 maintenance calories.
- 3
Subtract to lose weightA 500-a-day deficit gives roughly 2,123 calories, trending toward a pound a week.
- 4
Add to gain weightA 500-a-day surplus gives about 3,123 calories, for steady gain alongside training.
Maintenance, deficit, and surplus
Weight change comes down to one idea: calories in versus calories out. Eat at maintenance and your weight holds. Eat in a deficit, below maintenance, and your body taps stored energy, so you lose. Eat in a surplus and you gain. Because a pound of fat is roughly 3,500 calories, a 500-a-day deficit points to about a pound a week, which is a steady pace you'll actually keep. Bigger deficits lose faster but they're harder to stick with and can cost you muscle. The targets above give you a range, so you're not guessing. To track a weight change as a percent, the percentage calculator is handy, and you can check your weight band on the BMI calculator.
Frequently asked questions
What is BMR versus maintenance calories?
Your BMR is what you'd burn at complete rest, just keeping your body running. Maintenance calories are your BMR times an activity factor, covering everything you do in a day. Maintenance is the number you actually eat to hold your weight.
It depends on your age, sex, size, and how active you are. The calculator estimates your maintenance calories, the amount that holds your weight steady, then shows targets for losing or gaining. As a rough guide, many adult women maintain on about 1,800 to 2,200 calories and many adult men on 2,200 to 2,800, but you'll want your own number above, which beats any average.
This tool uses the Mifflin-St Jeor equation, the formula dietitians lean on most. It works out your basal metabolic rate from your weight, height, age, and sex, then multiplies by an activity factor to get the calories you burn in a day. To lose weight you eat below that number; to gain, above it. The result shows each target so you don't have to do the multiplying.
A calorie deficit means eating fewer calories than you burn, which is what drives weight loss. Roughly 3,500 calories equals a pound of fat, so a 500-a-day deficit trends toward about a pound a week. The calculator builds the deficits in for you: the mild, moderate, and larger weight-loss rows are just your maintenance number minus 250, 500, and 1,000.
Pick a weight-loss target above and aim to eat around that many calories a day, while keeping protein high and staying active. The moderate row, about 500 below maintenance, suits most people and points to roughly a pound a week. Going faster than the largest row isn't usually wise. Pair the target with the foods you enjoy so it's a plan you can keep.
Generally no. Eating very low, under about 1,200 calories for women or 1,500 for men, is hard to sustain and can leave you short on nutrients. If a weight-loss target above drops below those floors, you'll want to ease off to a smaller deficit or add activity instead. For a big change, it's worth checking in with a doctor or dietitian first.
No, they're solid estimates. The Mifflin-St Jeor formula is accurate for most people to within about 10%, but real metabolism varies with genetics, muscle, sleep, and more. Use the number as a starting point, track your weight for a couple of weeks, and adjust up or down if the scale isn't moving the way you expect.
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