Calorie Calculator

Estimate your daily calorie needs using the Mifflin-St Jeor equation — the formula recognized by the Academy of Nutrition and Dietetics as the most accurate for most adults — with a breakdown of calorie targets for maintaining, losing, or gaining weight.

How your calorie needs are calculated

The calculator works in two steps. First it estimates your BMR with the Mifflin-St Jeor equation:

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

Then it multiplies your BMR by an activity factor to get your TDEE — the calories you burn on a typical day:

Activity level	Multiply BMR by
Sedentary — little or no exercise	1.2
Lightly active — 1–3 days a week	1.375
Moderately active — 3–5 days a week	1.55
Very active — 6–7 days a week	1.725
Extra active — hard training or a physical job	1.9

Worked example

A 35-year-old woman who is 5 ft 5 in (165 cm) and weighs 150 lb (68 kg):

• BMR = 10 × 68 + 6.25 × 165.1 − 5 × 35 − 161 ≈ 1,376 calories
• Lightly active: 1,376 × 1.375 ≈ 1,892 calories a day to maintain her weight
• To lose about 1 lb a week: 1,892 − 500 ≈ 1,392 calories a day

Losing or gaining weight

The goals below the result use a common rule of thumb: about 3,500 calories equals one pound of body fat. Eating 500 calories a day below your TDEE adds up to roughly 3,500 a week, or about 1 lb. Real results vary — weight loss usually slows over time as your body adjusts — so check your progress every two to three weeks and adjust.

Many health professionals advise not going below about 1,200 calories a day for women or 1,500 for men without medical supervision, because it becomes hard to get enough nutrients.

Frequently asked questions

What formula does this use?

The Mifflin-St Jeor equation — the formula the Academy of Nutrition and Dietetics identifies as the most accurate for estimating resting energy needs in most adults, replacing the older Harris-Benedict equation.

What's the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is roughly the calories your body burns at complete rest just to function. TDEE (Total Daily Energy Expenditure) adds your activity level on top of that — it's the number to use for actual daily calorie targets.

How accurate is this?

It's a well-established estimate, typically within about 10% of measured energy expenditure for most healthy adults — but individual metabolism varies. Treat the result as a starting point to adjust from based on how your weight actually changes over a few weeks, not an exact number.

Is this safe to use for weight loss?

The mild and standard weight-loss targets shown (about a 250–500 calorie daily deficit) are the generally recommended range for gradual, sustainable weight loss. This tool isn't medical advice — talk to a doctor or dietitian before following a calorie target, especially for larger deficits, if you're pregnant or nursing, or have a health condition.

How many calories should I eat to lose weight?

Start with your TDEE and subtract 250–500 calories a day for a gradual loss of about ½ to 1 lb a week. Larger cuts can work in the short term but are harder to stick to and can cost muscle.

Should I eat back the calories I burn exercising?

Not if you've already chosen an activity level — your workouts are already counted in your TDEE. Adding exercise calories on top would count them twice.

This tool provides a general estimate for healthy adults and isn't a substitute for medical or dietary advice.