Calorie Deficit Calculator
Find out exactly how many calories to eat to reach your goal weight. Enter your stats, daily movement, training, target weight, and preferred deficit to get a daily calorie target, weekly loss rate, and estimated timeline.
A 500-calorie deficit is the classic rule of thumb, but it is not equally appropriate for every body. Check the result as a percentage of your TDEE. For a percentage-based reference, compare 25% of your TDEE with the fixed options above and choose the option that fits your starting point.
What Is a Calorie Deficit?
A calorie deficit means eating fewer calories than your body burns each day. When you maintain a deficit consistently, your body uses stored energy (primarily body fat) to make up the difference. This is the fundamental mechanism behind all fat loss, regardless of diet type.
The size of your deficit determines how fast you lose weight. A 500 calorie daily deficit produces roughly 1 pound of fat loss per week. Larger deficits speed up weight loss but increase the risk of muscle loss, fatigue, and metabolic adaptation.
Safe Deficit Ranges
250 cal/day (0.5 lb/week)
Slow and steady
500 cal/day (classic reference)
Check against your TDEE
750 cal/day (1.5 lbs/week)
Moderate aggressive
1000 cal/day (2 lbs/week)
Aggressive
A flat calorie deficit affects each body differently. Compare the result with your TDEE, use 25% as the default reference point, and choose a smaller deficit when the target reaches the planning floor.
High deficit warning
Targets near 1,000 calories below TDEE are aggressive. Use them for short phases, keep protein high, maintain resistance training, and avoid going below minimum calories without medical guidance.
How to Preserve Muscle During a Deficit
- •Eat enough protein. Aim for 1g per pound of body weight. Protein is the most important macro during a cut.
- •Keep lifting weights. Resistance training signals your body to preserve muscle. Do not switch to all cardio.
- •Use a moderate deficit. Losing 0.5-1% of body weight per week is optimal for muscle retention.
- •Sleep 7-9 hours. Recovery is when your body repairs muscle tissue. Sleep deprivation accelerates muscle loss during a cut.
Reviewed by Andrew Menechian, Head of Fitness, FitCommit
Andrew reviews FitCommit's calorie, macro, and body-composition methodology. His background includes 12+ years in fitness, PN1, PNC 1&2, Poliquin PICP 1&2, bodybuilding, powerlifting, and coaching education.
Frequently Asked Questions
What is a safe calorie deficit?
A safe deficit for most people is 500-750 calories per day, producing 1-1.5 lbs of weight loss per week. Going above 1000 cal/day deficit risks muscle loss, metabolic slowdown, and nutrient deficiencies. Women should generally not eat below 1200 calories/day and men below 1500 calories/day without medical supervision.
Will a 500 calorie deficit make me lose 1 pound per week?
In theory, yes. One pound of fat contains roughly 3,500 calories, so a 500 cal/day deficit equals 3,500 per week, or about 1 pound. In practice, weight loss is not perfectly linear. Water retention, hormonal fluctuations, and metabolic adaptation cause weekly weight to vary. Track over 2-4 weeks to see the real trend.
How fast can I lose weight without losing muscle?
Research suggests 0.5-1% of body weight per week is safe for muscle preservation. For a 180 lb person, that is 0.9-1.8 lbs per week. Key factors for preserving muscle: eat enough protein (1g per lb of body weight), continue resistance training, do not crash diet, and keep your deficit at 500-750 cal/day.
What is the minimum number of calories I should eat?
FitCommit's general-planning calculators stop calorie targets at 1,500 calories per day for men and 1,200 for women. These are planning guardrails, not individualized medical advice. If your target reaches the floor, choose a smaller deficit or speak with a qualified clinician before going lower.
Can I lose fat without losing muscle?
Yes, but it requires three things: (1) A moderate deficit (not extreme). (2) High protein intake, around 1g per pound of body weight. (3) Resistance training at least 3 times per week. Research shows trained individuals can maintain or even build muscle in a deficit when protein and training are sufficient.
Related Calculators
See Your Timeline Visually
FitCommit shows a week-by-week visual transformation timeline based on your body composition. AI body scan, TDEE, macros, and food tracking. Free trial.
Try FitCommit Free