All tools

Calorie Deficit Calculator

Calculate how many calories to eat per day to reach your weight goal. Based on your TDEE with a safe calorie deficit.

Files processed in your browser — never uploaded to our servers

BMI is a screening tool, not a diagnostic measure. Consult a healthcare professional for medical advice.

What is Calorie Deficit Calculator?

A calorie deficit occurs when you consume fewer calories than your Total Daily Energy Expenditure (TDEE), forcing your body to draw on stored energy — primarily body fat — to make up the shortfall. The widely cited rule that 3,500 calories equals one pound (about 0.45 kg) of fat loss is a useful approximation, but research shows the relationship is not perfectly linear: as you lose weight, your TDEE drops, your body adapts hormonally, and the rate of loss slows over time. For most adults, a moderate deficit of 250–500 kcal per day produces safe, sustainable fat loss of approximately 0.25–0.5 kg (0.5–1 lb) per week without triggering severe hunger or muscle loss. Protein intake becomes especially important during a deficit — eating at least 1.6–2.2 g of protein per kg of body weight helps preserve lean muscle mass while the body sheds fat.

How to use

  1. Enter your age, biological sex, weight, height, and activity level.
  2. Click Calculate to see your TDEE (maintenance calories).
  3. Review the deficit table: the 250 kcal/day deficit targets ~0.25 kg loss per week; the 500 kcal/day deficit targets ~0.5 kg per week.
  4. Pick the deficit level that fits your timeline and feels sustainable — faster is not always better.
  5. Set your daily calorie goal in a food tracking app (MyFitnessPal, Cronometer, etc.) and prioritize protein.
  6. Re-run the calculator every 3–4 weeks as your weight changes to keep the deficit accurate.

Why it matters

A calorie deficit that is too aggressive leads to muscle loss, fatigue, nutrient deficiencies, and rebound weight gain. A deficit that is too small yields frustratingly slow progress. Calculating your personal deficit based on your actual TDEE — rather than using a generic 1,200 kcal diet — protects your metabolic health and makes the process sustainable long-term.

Pro tip

Never let your daily calories drop below your BMR for extended periods. Eating below BMR forces your body to break down muscle for energy, reduces thyroid output, and slows metabolism in ways that can persist long after the diet ends. A 20% deficit below TDEE is generally the safe maximum for most people.

Frequently Asked Questions

Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a day, accounting for your basal metabolic rate (BMR) and physical activity. It tells you how many calories you need to maintain your current weight.
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain basic functions like breathing, circulation, and cell production. It represents about 60–75% of your TDEE.
A safe calorie deficit is 250–500 calories below your TDEE per day, resulting in approximately 0.25–0.5 kg (0.5–1 lb) of weight loss per week. Avoid deficits larger than 1,000 calories without medical supervision.
This calculator uses the Mifflin-St Jeor equation, which is considered the most accurate for estimating BMR without laboratory measurements: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 (male) or −161 (female).