Calorie Deficit Calculator
Calculate the daily calorie deficit needed to reach your goal weight in a target timeframe.
Results
Visualization
How It Works
The calorie deficit calculator determines how many fewer calories you need to eat each day to reach your goal weight within your chosen timeframe. It uses the principle that roughly 7,700 calories equals one kilogram of body fat to project your weight loss trajectory.
The Formula
Variables
- Current_Weight — Your current body weight in kilograms
- Goal_Weight — Your target body weight in kilograms
- 7700 — Approximate calories in one kilogram of body fat
- TDEE — Total Daily Energy Expenditure - your maintenance calories
- Daily_Deficit — Calories below TDEE you must eat each day
Worked Example
Starting at 85 kg with a goal of 75 kg over 12 weeks: Total loss = 10 kg = 77,000 kcal. Daily deficit needed = 77,000 / 84 days = 917 kcal. With a TDEE of 2,200 kcal, daily target = 2,200 - 917 = 1,283 kcal. Since this is above 1,200 minimum, the plan is feasible. Weekly loss = 0.83 kg.
Practical Tips
- Never go below 1,200 kcal/day for women or 1,500 for men without medical supervision.
- A deficit of 20-25% of TDEE is aggressive but sustainable for most people; beyond 30% risks muscle loss.
- Increase your timeframe if the required deficit exceeds 1,000 kcal/day for a safer approach.
- Pair your deficit with resistance training to preserve lean mass during weight loss.
- Weight loss is not linear - expect plateaus every 4-6 weeks as your body adapts and TDEE decreases.
Frequently Asked Questions
Is 1 kg per week weight loss safe?
For most people, 0.5-1 kg per week is safe and sustainable. Those with more weight to lose can safely lose up to 1% of body weight per week. Faster rates increase risk of muscle loss and metabolic slowdown.
Why does the calculator set a 1,200 kcal minimum?
Below 1,200 kcal it becomes very difficult to meet essential vitamin and mineral needs through food alone. Very low calorie diets should only be followed under medical supervision with appropriate supplementation.
Should I eat back exercise calories?
Eating back roughly 50% of exercise calories is a reasonable approach. Fitness trackers tend to overestimate calorie burn by 30-50%, so eating back the full amount often eliminates your deficit.
Why has my weight loss stalled?
Plateaus happen because your TDEE drops as you lose weight (smaller body burns fewer calories). Recalculate your TDEE with your new weight, check for calorie creep in tracking, and consider a 1-2 week diet break at maintenance.
Does the 7,700 calories per kg rule always apply?
It is a useful approximation but not perfectly precise. In reality, weight loss includes some water and lean tissue, not just fat. The ratio varies by individual body composition, deficit size, and protein intake.