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Calorie deficit calculator
Results are estimates. Use as a starting point and adjust based on real-world progress over 2–3 weeks.
Your results
—
over the next 12 weeks
Your numbers are above — adjust your inputs anytime, or use tracking to stay close to your daily target.
What is a calorie deficit?
A calorie deficit happens when you consume fewer calories than your body burns in a day. Your body's total daily energy expenditure (TDEE) includes everything it burns — breathing, digestion, movement, and exercise. When your intake falls below this number, your body turns to stored fat for fuel, resulting in weight loss.
The most sustainable deficits sit between 300–500 calories per day, producing roughly 0.3–0.5 kg (0.7–1 lb) of fat loss per week. Larger deficits accelerate loss but increase the risk of muscle breakdown and nutrient deficiency.
How many calories should I eat to lose weight?
There is no universal answer — it depends on your height, weight, age, sex, and activity level. That's why calculators like this one use the Mifflin-St Jeor equation, widely considered the most accurate formula for estimating your resting metabolic rate (BMR). Your BMR is then multiplied by an activity factor to give your TDEE — and your target is TDEE minus your chosen deficit.
A common starting point is eating at a 500 calorie deficit per day, which targets approximately 0.5 kg (1 lb) of fat loss per week.
What is a safe calorie deficit?
Most nutrition experts consider a deficit of 250–750 calories per day safe for healthy adults. Going below 1,200 kcal/day (women) or 1,500 kcal/day (men) is not recommended without medical supervision — it risks muscle loss, fatigue, and nutritional deficiencies.
If you're new to dieting, start small (250–300 kcal/day) and increase gradually as your body adjusts.
How to calculate your calorie deficit manually
- Calculate BMR — Mifflin-St Jeor: (10 × kg) + (6.25 × cm) − (5 × age) + 5 (men) or −161 (women)
- Multiply BMR by your activity factor (1.2 sedentary → 1.9 athlete) to get TDEE
- Subtract your target deficit — that's your daily calorie goal
Example: 30-year-old man, 180 cm, 85 kg, moderately active → TDEE ~2,750 kcal. A 500 kcal deficit = 2,250 kcal/day target.
Calorie deficit vs calorie restriction
Calorie restriction is a blanket food reduction with no individual baseline. Calorie deficit is targeted — you calculate exactly what your body burns, then eat a specific amount less. The deficit approach is more precise and sustainable because it's based on your actual metabolism.
What macros should I eat on a calorie deficit?
Protein is the most important macro when cutting. A higher intake (~40% of calories) preserves muscle mass during a deficit. LeanCalc uses 40% protein / 35% carbs / 25% fats — a well-researched split for fat loss while maintaining strength and energy.
Frequently asked questions
Can I lose weight without counting macros?
Yes. Macros help with structure and muscle retention, but a calorie deficit is the main driver of fat loss. Tracking macros simply makes the process easier to manage.
Why does my projected timeline look long?
Because slower, sustainable fat loss works better over time. Bigger deficits look faster on paper but are harder to maintain and increase the risk of muscle loss.
Should I eat back exercise calories?
Most people overestimate calories burned during exercise. Monitor real-world progress over 2–3 weeks before adjusting your target upward.
How accurate is this calculator?
LeanCalc uses the Mifflin-St Jeor equation — the most validated BMR formula for healthy adults. Treat results as a strong starting estimate, then adjust based on real progress tracking.