Health & fitness
Calorie Calculator
This calculator estimates how many calories you should eat each day to reach a specific goal — losing weight, holding steady, or gaining. Enter your sex, age, height, weight and activity level in U.S. customary units (feet, inches and pounds) or metric, pick a goal, and it works out your maintenance calories (TDEE) from the Mifflin-St Jeor equation, then adds or subtracts a daily amount to match your target. Weight change comes down to energy balance: eat fewer calories than you burn and you lose, eat more and you gain. The standard rule of thumb is that about 3,500 calories equals roughly one pound of body fat, so a 500-calorie daily deficit aims at about a pound a week. It updates as you type, runs entirely in your browser, and shows the math below. This is general information only, not medical advice — consult a licensed professional before changing your diet.
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These are estimates, not a diagnosis. Don't eat below about 1,500 calories (men) or 1,200 (women) without professional guidance.
How the calorie calculator works
The tool runs in three steps. First it finds your BMR with the Mifflin-St Jeor equation. Then it multiplies BMR by your activity factor to get your maintenance calories (TDEE). Finally it adds or subtracts a daily amount for your goal to produce your target. Imperial inputs are converted to metric first, so the result is identical either way.
calorie target formula
Target = (BMR × activity) + goal adjustment BMR (men) = 10W + 6.25H − 5A + 5 BMR (women) = 10W + 6.25H − 5A − 161where: W = weight in kg, H = height in cm, A = age in years activity = 1.2 (sedentary) to 1.9 (extra active) goal: −500 cal/day ≈ lose 1 lb/week; +500 ≈ gain 1 lb/week (based on ≈ 3,500 calories per pound of fat)
Notes & assumptions
- The 3,500-calories-per-pound rule is a useful approximation, not an exact law of physics.
- Very large deficits can backfire — slower, steadier loss is easier to keep off.
- Calculations are for general information only and are not medical advice — consult a healthcare professional before changing your diet.
Worked example
Say you're a 30-year-old man in Arizona, 5 ft 9 in and 160 lb, who exercises moderately and wants to lose weight. Converting gives 175.26 cm and 72.57 kg, and the Mifflin-St Jeor men's formula returns a BMR of about 1,676 calories. Multiply by the moderately active factor (1.55) for a maintenance TDEE of about 2,598 calories. To lose roughly one pound a week, subtract 500: 2,598 − 500 = about 2,098 calories per day. Choose the "maintain" goal instead and your target is just the TDEE of 2,598; choose "gain 1 lb/week" and it rises to about 3,098. Change any input above and every number recalculates instantly.
Frequently asked questions
How many calories should I eat to lose weight?
To lose weight you need to eat fewer calories than you burn. A common, sustainable starting point is a deficit of about 500 calories a day below your maintenance (TDEE) level, which targets roughly one pound of fat loss per week. Faster loss is possible with a larger deficit, but it's harder to sustain and risks losing muscle. This calculator does the math for you once you pick a loss goal — but treat the number as a starting estimate and adjust based on real results.
Is it safe to eat very few calories?
Eating too little can be risky. As a general guide, adult women shouldn't drop below about 1,200 calories a day and adult men below about 1,500 without medical supervision, because very-low-calorie diets can cause nutrient deficiencies, muscle loss and a slowed metabolism. If our calculator suggests a target below those floors for an aggressive goal, choose a gentler goal instead — and always consult a doctor or registered dietitian before starting a restrictive plan.
Why does a pound equal 3,500 calories?
The "3,500 calories per pound" figure is a long-standing estimate of the energy stored in a pound of body fat. It's why a daily deficit of 500 calories (500 × 7 = 3,500 per week) is often cited as roughly one pound of weekly loss. In practice it's an approximation — metabolism adapts as you lose weight, so real-world results vary. It's still a handy planning rule, just not an exact guarantee.
Should I eat the same calories every day?
You can, and consistency makes tracking easier, but you don't have to. What matters most for weight change is your average intake over the week relative to your TDEE. Some people prefer to eat a little more on training days and less on rest days. As long as the weekly total lands near your target, the day-to-day distribution is mostly a matter of personal preference and what keeps you consistent.
How accurate is this calorie target?
It's a solid estimate for most healthy adults, but not a precise prescription. It depends on the accuracy of your inputs — especially how honestly you rate your activity level — and on the Mifflin-St Jeor equation, which can't see your body composition or genetics. Use the target as a starting point, track your weight over two to three weeks, and adjust up or down by 100 to 200 calories if the scale isn't moving the way you expect. For personalized advice, see a healthcare professional.