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Calculator Answers

Calorie Calculator

Source: Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247 · Source verified July 22, 2026

Blake Boege
Written by Blake Boege · Founder, Calculator Answers

A calorie calculator is a nutritional tool that estimates the daily caloric intake required for a person to maintain, lose, or gain weight. It first calculates the Total Daily Energy Expenditure (TDEE) using metabolic formulas like the Mifflin-St Jeor equation, then applies a caloric deficit or surplus based on the user's weight management goals. It is the foundational tool for modern macronutrient and calorie-tracking diets.

Find how many calories you should eat per day based on your age, sex, weight, height, activity level, and weight goal. The calculator uses the Mifflin-St Jeor equation — the most accurate BMR formula for the general population — and shows your daily targets for weight loss, maintenance, and gain side-by-side so you can compare options.

Quick Answer

Calculate exactly how many calories you should eat per day to lose weight, gain muscle, or maintain your current weight based on your age, size, and activity level.

Sex

Units

lb
Height
ft
in
Daily Calorie Target

Your daily calorie target

2,263 calories

to lose ~1 lb per week

Your BMR1,783 calories
Your TDEE (maintenance)2,763 calories
Goal calories2,263 calories
Weekly weight change estimate-1.00 lbs per week

All Goal Targets

Maintenance2,763 calories
Mild weight loss (-250 cal/day)2,513 calories
Weight loss (-500 cal/day)2,263 calories
Extreme weight loss (-1000 cal/day)1,763 calories
Mild weight gain (+250 cal/day)3,013 calories
Weight gain (+500 cal/day)3,263 calories
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Examples

25-year-old man, 180 lbs, 5'10", moderately active, maintain

~2,650 calories

35-year-old woman, 140 lbs, 5'4", lightly active, lose weight

~1,500 calories

45-year-old man, 200 lbs, 6'0", sedentary, lose weight

~2,100 calories

22-year-old woman, 125 lbs, 5'7", very active, gain muscle

~2,750 calories

How it works

Formula · BMR (male) = 10 × weight kg + 6.25 × height cm − 5 × age + 5; BMR (female) = 10 × weight kg + 6.25 × height cm − 5 × age − 161; TDEE = BMR × activity factor

The calculator runs in three steps:

  1. Calculate your BMR (Basal Metabolic Rate) — the calories your body burns at rest just keeping you alive. The Mifflin-St Jeor equation uses your weight, height, age, and biological sex to estimate this.
  2. Multiply BMR by your activity multiplier (1.2 for sedentary up to 1.9 for extra active) to get your TDEE (Total Daily Energy Expenditure) — your maintenance calories.
  3. Adjust TDEE by the figure you choose. At the static 3,500 calories per pound conversion, a 500 calorie daily deficit works out to about 1 lb a week and a 500 calorie daily surplus to about 1 lb of gain. Both are subtraction and addition against the maintenance estimate rather than recommendations.

Formulas

Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5

Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

TDEE = BMR × activity multiplier

Daily calorie target = TDEE ± goal adjustment

Activity level guide

Choose the activity level that matches your weekly routine.

  • Sedentary: Desk job, no formal exercise. Multiplier: 1.2
  • Lightly active: Light exercise 1-3 days/week (walking, easy bike rides, light yoga). Multiplier: 1.375
  • Moderately active: Moderate exercise 3-5 days/week (jogging, lifting, sports). Multiplier: 1.55
  • Very active: Hard exercise 6-7 days/week (intense training, competitive sports). Multiplier: 1.725
  • Extra active: Very hard exercise plus physical job or training 2x/day. Multiplier: 1.9

Most people overestimate their activity level. If you're not sure, pick one step lower than you think — it's easier to add calories later if you're losing weight too fast.

How to set your goal

For weight loss: a 500 calorie daily deficit works out to about 1 lb a week at the static conversion. This page does not name a recommended pace, because the figure it used to give was below what the guidelines publish rather than in the middle of them: NHLBI recommends 500 to 1,000 calories a day and AHA/ACC/TOS prescribes 500 or 750. The arithmetic is the same whichever you choose; the choice is not this page's to make.

For weight maintenance: eat at TDEE. Weight fluctuates day-to-day from water and food volume, so check weekly averages, not daily numbers.

For weight gain: a surplus is intake above maintenance. One named body does publish a figure, for a different question: the NHS tells underweight adults they "could try adding around 300 to 500 extra calories a day", which is about gaining weight generally rather than gaining muscle, and note that it is 300 to 500 rather than the 250 to 500 that circulates. For MUSCLE gain specifically no body gives a number: the ISSN position stand on diets and body composition declines to name one and says the magnitude depends on training status, and the ACSM, Academy of Nutrition and Dietetics and Dietitians of Canada joint position stand publishes no daily surplus either. The nearest published figures are a percentage of maintenance rather than a fixed count. The mechanism that is well supported is directional: a larger surplus adds a greater share of fat rather than lean tissue.

Recalculate every 10-15 lbs of weight change. Your calorie needs decrease as you lose weight.

Worked example

30-year-old woman, 150 lbs, 5'5" (165 cm), moderately active, wants to lose weight.

  • Step 1: Convert weight: 150 lbs = 68 kg
  • Step 2: BMR = (10 × 68) + (6.25 × 165) − (5 × 30) − 161
    = 680 + 1031.25 − 150 − 161
    = 1,400 calories/day
  • Step 3: TDEE = 1,400 × 1.55 (moderately active) = 2,170 calories/day
  • Step 4: Weight loss target = 2,170 − 500 = 1,670 calories/day

She should eat about 1,670 calories per day to lose roughly 1 lb per week.

Common calorie calculation mistakes

  • Overestimating activity level. Most people who pick 'moderately active' should actually pick 'lightly active.' If you have a desk job and work out 3x a week, you're 'lightly active,' not 'moderately active.'
  • Ignoring weekly averages. Weight fluctuates 2-5 lbs day-to-day from water, sodium, food volume, and bowel movements. Track weekly averages instead of daily numbers.
  • Not recalculating after weight change. Your calorie needs drop as you lose weight. A 200-lb person who reaches 170 lbs needs roughly 150-200 fewer daily calories. Recalculate every 10-15 lbs.
  • Going too low too fast. Cutting more than 1000 calories below TDEE typically backfires — energy crashes, muscle loss, slowed metabolism, and rebound weight gain when you stop.
  • Trusting calorie estimates as exact. The Mifflin-St Jeor formula is accurate within ±10% for most people. Track for 2-3 weeks and adjust based on actual results.
  • Forgetting that "calories burned" estimates from fitness trackers are often inflated. Fitness watches overestimate exercise calorie burn by 25-50%. Use your TDEE target rather than 'eating back' exercise calories.

Related calculators

Disclaimer. This calorie calculator provides estimates based on the Mifflin-St Jeor equation. Individual calorie needs vary based on genetics, medications, body composition, and other factors not captured by the formula. Consult a registered dietitian or doctor for personalized nutrition advice, especially if you have a medical condition or are pregnant.

Related Calculators

More tools from Health

TDEE CalculatorEstimate your Total Daily Energy Expenditure from sex, age, height, weight, and activity — with maintenance, cut, and bulk targets.

Frequently asked questions

It depends on your age, sex, weight, height, activity level, and goals. As a rough average: sedentary women need 1,600-2,000 calories; active women 2,000-2,400; sedentary men 2,000-2,600; active men 2,400-3,000. Use the calculator above for your personalized number.

Mifflin-St Jeor is the most accurate BMR formula for the general population. That judgement is not Mifflin's own: it comes from Frankenfield, Roth-Yousey and Compher in the Journal of the American Dietetic Association in 2005, who compared the equations and found Mifflin-St Jeor "the most reliable, predicting RMR within 10% of measured in more nonobese and obese individuals than any other equation". The 82% figure circulates widely from that comparison but this page could not read it verbatim, so treat it as approximate. It's the recommended formula by the American Dietetic Association. For very lean athletes who know their body fat percentage, the Katch-McArdle formula can be more accurate.

That is arithmetic, and here it is: at the static conversion of 3,500 calories to a pound, a 500 calorie daily deficit is 3,500 a week, which is one pound. The conversion is a 1958 average rather than a constant, and because energy needs fall as body mass falls, a fixed daily deficit produces less change over time than the multiplication suggests. Note also that the published guideline figures are LARGER than 500: the NHLBI obesity guideline recommends a deficit of 500 to 1,000 calories a day, and the 2013 AHA/ACC/TOS guideline prescribes 500 or 750. Which deficit suits you is not something this page can judge from sex, age, height, weight and an activity setting.

Most often the activity level: most people sit one notch lower than they pick. The other possibility is that the deficit you asked for is large relative to your maintenance estimate, and the page will show you that without judging it. This page previously called a 500 calorie deficit the sweet spot and said larger deficits typically backfire. Neither statement had a source, and both point away from what the guidelines actually publish, which is 500 to 1,000 a day at NHLBI and 500 or 750 at AHA/ACC/TOS. If a target looks wrong for you, that is a question for a clinician or a registered dietitian rather than for this arithmetic.

BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just keeping organs functioning. TDEE (Total Daily Energy Expenditure) is BMR plus all activity (exercise, walking, fidgeting, daily life). TDEE is what you eat to maintain weight; BMR is the foundation.

Generally no. Fitness trackers overestimate exercise calorie burn by 25-50%. Your activity multiplier already accounts for typical exercise. If you eat back inflated tracker calories, you'll wipe out your deficit. Better approach: pick your target from this calculator and stick to it regardless of daily exercise variation.

This page used to call 1,200 for women and 1,500 for men a floor below which you need medical supervision. No body publishes that pair as a floor. Those numbers are the bottom of the intake range the 2013 AHA/ACC/TOS guideline tells clinicians to PRESCRIBE for weight loss, which is what to eat rather than where to stop, and the 1998 NHLBI guideline recommends 1,000 to 1,200 a day for most women as ordinary dietary therapy with no supervision attached. Where the guidelines actually attach medical supervision is under 800 calories a day, the very-low-calorie diet line. The nearest real boundaries elsewhere are NICE, which confines 800 to 1,200 a day to a specialist service and publishes no separate figure for men, and the NIDDK Body Weight Planner, which floors its own tool at 1,000 a day for everyone because nutrient targets cannot be met below it. Very low intakes do carry the risks this page listed; the numbers attached to them here were this page's own.

Recalculate every 10-15 lbs of weight change, or when your activity level changes significantly, or if your weight loss/gain stalls for 2-3 weeks. Your calorie needs decrease as you lose weight (a 200-lb body burns more than a 150-lb body even at rest).

Men typically have more lean muscle mass than women at the same body weight, and muscle burns more calories at rest than fat. Men also tend to have higher testosterone, which supports metabolism. The Mifflin-St Jeor formula accounts for this with a sex-specific constant (+5 for men, -161 for women).

Yes, if you selected the correct activity level. The activity multiplier (1.2 to 1.9) accounts for both daily activity and exercise. You don't need to separately add exercise calories on top of your target — the activity level you picked already includes it.