Calorie Calculator
Find your daily calorie needs to maintain, lose or gain weight, based on age, sex, height, weight and activity level. Includes safe deficit guidance.
How your calorie target is built
Three steps: estimate your resting burn (BMR) with the Mifflin-St Jeor equation, scale it by an activity
factor to get your maintenance calories, then shift that maintenance for your goal. Roughly 7,700 kcal
corresponds to 1 kg of body fat, so a 0.5 kg/week change needs about 550 kcal/day.
BMR = 10 × kg + 6.25 × cm − 5 × age + 5 (men) or − 161 (women)
Maintenance = BMR × activity factor (1.2 – 1.9)
Goal calories = Maintenance ± 275 (0.25 kg/wk) or ± 550 (0.5 kg/wk)
Worked example
A 30-year-old man, 70 kg (154 lb), 170 cm (5′7″), moderately
active: BMR ≈ 1,618 kcal, maintenance ≈ 1,618 × 1.55 = 2,507 kcal/day. To maintain, he eats
about 2,507 kcal; to lose 0.5 kg per week he would target 2,507 − 550 ≈ 1,957 kcal/day.
Why crash deficits backfire
Cutting far below your needs feels productive but works against you. Very low intakes make adequate protein and
micronutrients nearly impossible, so a larger share of the weight lost is muscle — which lowers the very
metabolism you rely on. Hunger hormones rise, energy and training quality fall, and adherence collapses;
research on aggressive dieting consistently shows higher dropout and greater regain. That is why this
calculator never recommends less than 1,200 kcal/day for women or
1,500 kcal/day for men: if your chosen goal would go below that, we raise it to the floor and
flag it. A smaller deficit you can hold for months beats a huge one you abandon in two weeks.
Limitations
Every step here is an estimate: the formula carries about ±10% error, activity multipliers are broad brackets,
and food-label calories are imprecise. Use the number as a starting point, track your weight trend for two to
three weeks, and adjust by 100–150 kcal at a time. People with medical conditions, pregnant or breastfeeding
women, and teenagers should get individual advice instead.
Frequently asked questions
How are my daily calories calculated?
We estimate your BMR with the Mifflin-St Jeor equation, multiply it by your activity level to get maintenance calories (TDEE), then subtract or add a fixed amount for your goal: about 275 kcal/day per 0.25 kg (0.55 lb) of weekly change.
Why is my target never below 1,200 (women) or 1,500 (men) kcal?
Below those intakes it is very hard to meet protein, vitamin and mineral needs, and aggressive deficits accelerate muscle loss and rebound. This calculator floors your target at those minimums and shows a warning — pick a slower rate of loss or add activity instead.
How fast can I safely lose weight?
Most guidelines suggest 0.25–0.5 kg (0.5–1 lb) per week, roughly a 275–550 kcal daily deficit. Faster loss usually means more muscle loss, more hunger and a higher chance of regaining the weight.
Do I need to hit the number exactly every day?
No — your weekly average matters far more than any single day. Being 100 kcal over on Tuesday and under on Wednesday nets out. Track the trend of your body weight over 2–3 weeks and adjust.
Why am I not losing weight at my calculated deficit?
Formulas carry roughly ±10% error, portion logging tends to undercount, and metabolism adapts slightly as you diet. If your weight trend is flat after three weeks, reduce intake by 100–150 kcal or add daily movement, and re-measure.
Should I eat back exercise calories?
Your activity multiplier already includes your typical exercise, so do not add workout calories on top. Only adjust if your routine genuinely changes — then pick a different activity level.
This tool provides general health information, not medical advice. Consult a healthcare professional before making decisions based on it.