How your calorie needs are calculated
Step 1 — BMR. Your basal metabolic rate is estimated with the Mifflin-St Jeor equation:
Women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161
Step 2 — TDEE. BMR is multiplied by an activity factor: 1.2 (sedentary), 1.375 (light), 1.55 (moderate), 1.725 (very active) or 1.9 (extra active).
Step 3 — Goal. About 7,700 kcal equals 1 kg of body weight (3,500 kcal per pound), so losing 0.5 kg a week needs a daily deficit of about 550 kcal.
Making the numbers work
- Pick your activity level honestly. Most people with desk jobs who exercise a few times a week fit “lightly” or “moderately active”.
- Prioritize protein when cutting calories to preserve muscle — see the macro calculator.
- Recalculate as your weight changes. A smaller body burns fewer calories, so your target drops over time.
- Use a trend, not a single weigh-in. Daily weight can swing 1–2 kg with water and food.
These are estimates for healthy adults. Pregnant or breastfeeding women, people with medical conditions and competitive athletes should consult a doctor or registered dietitian.
How to use the calculator
- Enter your age, sex, height and weight.
- Choose the activity level that matches a typical week — be honest; most people overestimate activity.
- Choose your goal: maintain, lose or gain weight.
- Read your daily calorie target and how it was calculated.
Calories by activity level
For the example man (30 years, 180 cm, 80 kg, BMR 1,780 kcal):
| Activity level | Multiplier | Maintenance (example man) | Lose ≈0.5 kg/week |
|---|---|---|---|
| Sedentary (little exercise) | ×1.2 | 2,136 | 1,636 |
| Light (1–3 days/week) | ×1.375 | 2,448 | 1,948 |
| Moderate (3–5 days/week) | ×1.55 | 2,759 | 2,259 |
| Very active (6–7 days/week) | ×1.725 | 3,070 | 2,570 |
| Extra active (physical job + training) | ×1.9 | 3,382 | 2,882 |
How fast should you lose weight?
A daily deficit of about 500 kcal is a common starting point and typically leads to losing around 0.5 kg (1 lb) a week at first. The old rule that 3,500 kcal equals one pound of fat overestimates long-term loss, because your energy needs fall as you get lighter. Research models from the U.S. National Institutes of Health show weight loss slowing over months even if you keep eating the same amount. Losing about 0.5–1% of body weight per week preserves more muscle and is easier to sustain than crash dieting. Guidelines generally advise not going below about 1,200 kcal a day for women or 1,500 for men without medical supervision.
Gaining weight or muscle
For muscle gain, a small surplus of 250–500 kcal a day combined with strength training limits fat gain. Beginners can expect roughly 0.25–0.5 kg (0.5–1 lb) a week of total weight gain; experienced lifters gain muscle more slowly and need a smaller surplus.
Making the target work in real life
- Track for two weeks and compare your average weight trend with the prediction. If the scale doesn’t move as expected, adjust by 100–200 kcal.
- Prioritize protein and fiber — they keep you full on fewer calories.
- Watch liquid calories: sugary drinks, juice, specialty coffees and alcohol add up quickly without filling you up.
- Don’t “eat back” all exercise calories shown by fitness trackers; they often overestimate energy burned.
- Sleep 7–9 hours: short sleep increases hunger hormones and cravings.
Split your calories into protein, carbs and fat with the macro calculator.