About the Calorie Calculator
This calorie calculator estimates how many calories you need each day. It first works out your basal metabolic rate (BMR) with the Mifflin-St Jeor equation, multiplies it by an activity factor to get your maintenance calories, and then adds or subtracts a daily amount to match your goal — whether that is holding steady, losing half a pound to two pounds a week, or gaining weight.
It is meant for anyone who wants a sensible starting number for a diet, meal plan or calorie-tracking app: people starting a weight-loss plan, athletes trying to eat enough, or anyone curious whether their current intake matches their needs. The table shows every goal side by side so you can choose a pace you can sustain.
The weekly weight change uses the common rule of thumb that about 3,500 kcal equals one pound (7,700 kcal per kilogram) of body weight. Real progress usually slows over time as your body gets smaller, so re-run the calculator every 5–10 lb (2–5 kg) and adjust based on what the scale actually does over 2–4 weeks.
With the default inputs, the daily calories for your goal is 2,224 kcal/day. Change any value above to recalculate instantly.
How to use the calorie calculator
- 1Select your sex and enter your age.
- 2Choose US or metric units and enter your height and weight.
- 3Pick the activity level that matches a typical week, not your best week.
- 4Choose a goal: maintain, lose or gain, and how fast.
- 5Use the daily calorie target as a starting point and adjust after 2–4 weeks of tracking.
Formula and method
Resting energy use is estimated with the Mifflin-St Jeor equation, which is generally the most accurate of the common prediction equations for healthy adults. It is multiplied by an activity factor from 1.2 (sedentary) to 1.9 (hard daily training or a physical job) to estimate total daily energy expenditure, also called maintenance calories.
Your goal adds or removes a fixed number of calories per day: 250 kcal for about half a pound a week, 500 kcal for about one pound, and 1,000 kcal for about two pounds. The weekly change uses the 3,500 kcal per pound (7,700 kcal per kg) rule of thumb, which is a reasonable estimate for the first weeks but overstates long-term loss because energy needs fall as weight falls.
- W
- Body weight in kilograms
- H
- Height in centimetres
- A
- Age in years
Worked examples
35-year-old man, 5 ft 10 in, 180 lb, moderately active, losing 1 lb/week
He weighs 81.6 kg and is 177.8 cm tall, so Mifflin-St Jeor gives a BMR of about 1,758 kcal/day. Multiplying by 1.55 for moderate activity gives maintenance of about 2,724 kcal. Subtracting 500 kcal a day for a one-pound-a-week loss leaves a target of about 2,224 kcal/day.
28-year-old woman, 165 cm, 65 kg, lightly active, maintaining
BMR = 10 × 65 + 6.25 × 165 − 5 × 28 − 161 = 1,380 kcal/day. With a light-activity factor of 1.375 she needs about 1,898 kcal a day to keep her weight stable.
22-year-old man, 6 ft 1 in, 150 lb, very active, gaining 1 lb/week
At 68 kg and 185.4 cm his BMR is about 1,734 kcal/day, and his very active lifestyle raises maintenance to about 2,992 kcal. A 500 kcal surplus for roughly one pound a week of gain means eating about 3,492 kcal a day.
Frequently asked questions
How many calories should I eat a day?+
It depends on your size, age, sex and activity. Many adults need roughly 1,600–2,400 kcal (women) or 2,000–3,000 kcal (men) to maintain weight, according to the estimates in the 2020–2025 Dietary Guidelines for Americans. This calculator personalises that estimate from your own numbers.
How many calories should I cut to lose 1 pound a week?+
About 500 kcal per day below maintenance, which adds up to roughly 3,500 kcal a week. That is a rule of thumb: real loss tends to be a little faster at first (water) and slower later as your maintenance calories fall.
Is 1,200 calories a day enough?+
For many women 1,200 kcal is a common lower limit without medical supervision, and around 1,500 kcal for men. Going lower makes it hard to meet protein, vitamin and mineral needs, so a smaller deficit is usually more sustainable.
Should I eat back the calories I burn exercising?+
This calculator already includes exercise in the activity level, so do not add workout calories on top unless you picked "sedentary". Fitness trackers often overestimate calories burned, so eating back all of them can stall progress.
Why am I not losing weight on my calorie target?+
Common reasons are underestimating portions, weekend intake, drinks and cooking oils, or overestimating activity. Weigh yourself several times a week and compare 2–3 week averages; if there is no change, reduce intake by 100–200 kcal.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.