Calorie Deficit Calculator
Enter your current weight, goal weight, and timeframe. We'll calculate the exact daily deficit — and tell you whether it's sustainable.
How the calorie deficit is calculated
One kilogram of body fat stores approximately 7,700 kcal of energy. To lose a given amount of fat in a set number of weeks, you need to create a total energy deficit equal to that fat mass × 7,700, spread across the available days. The result is your required daily deficit.
The tool then rates the deficit: under 300 kcal/day is conservative (slow but preserves muscle), 300–600 kcal/day is the moderate sweet spot most coaches recommend, and above 600 kcal/day is aggressive — possible short-term but associated with muscle loss, hormonal disruption, and increased diet fatigue without sufficient protein.
To translate a deficit into actual food intake, first calculate your TDEE (maintenance calories), then subtract your daily deficit. That is your calorie target.
Frequently Asked Questions
- How many calories are in a kilogram of fat?
- One kilogram of body fat contains approximately 7,700 kcal of stored energy. This figure accounts for the fact that adipose tissue is not pure fat — it also contains water and connective tissue. The calculator uses this figure to convert your fat-loss goal into a total calorie deficit.
- What is a safe calorie deficit?
- A deficit of 300–500 kcal/day is widely considered moderate and sustainable for most people. It produces roughly 0.3–0.5 kg of fat loss per week and preserves muscle mass when protein intake is sufficient (1.6–2.2 g/kg bodyweight). Deficits above 750 kcal/day significantly increase the risk of muscle loss, hormonal disruption, and diet fatigue.
- Why is 1 lb per week the standard recommendation?
- One pound (0.45 kg) of fat represents ~3,500 kcal — equivalent to a 500 kcal/day deficit. This rate sits in the moderate zone, producing visible progress without the metabolic adaptation or muscle-loss risk of more aggressive cuts.
- Should I eat back exercise calories?
- If your TDEE was calculated using an accurate activity multiplier, no — exercise is already factored in. If you use a sedentary TDEE and track exercise separately, eating back roughly 50% of estimated calories burned is a reasonable buffer for exercise tracking inaccuracy.