Calorie Deficit Calculator
Find the precise daily calorie intake that will move you toward your goal — whether that's losing fat, maintaining weight, or building muscle.
What is a Calorie Deficit?
A calorie deficit occurs when you consume fewer calories than your body burns in a day. Since 1 kg of body fat contains approximately 7,700 kilocalories of stored energy, a consistent deficit of 500 kcal/day creates a weekly deficit of 3,500 kcal — theoretically resulting in roughly 0.5 kg of fat loss per week.
In practice, the relationship is not perfectly linear. As you lose weight, your BMR decreases, your body becomes more efficient, and hormonal adaptations (lower leptin, higher ghrelin) can increase appetite and reduce spontaneous movement. This means your actual weight loss will slow over time even at the same calorie intake.
For muscle gain, a modest calorie surplus is needed to provide the building blocks and energy for muscle protein synthesis. A surplus of 250–500 kcal/day ("lean bulk") generally maximises muscle growth while minimising excessive fat gain.
How to Choose Your Deficit Size
| Goal | Daily Deficit/Surplus | Expected Weekly Change |
|---|---|---|
| Aggressive fat loss | −750 kcal | −0.7 kg fat |
| Moderate fat loss | −500 kcal | −0.5 kg fat |
| Slow/comfortable fat loss | −250 kcal | −0.25 kg fat |
| Maintenance | 0 | 0 |
| Lean bulk | +250–500 kcal | +0.1–0.2 kg muscle |
Worked Examples
Example 1: Weight loss goal, 32F, sedentary, TDEE 1,800 kcal.
Target deficit: −500 kcal. Daily intake = 1,800 − 500 = 1,300 kcal/day. Expected loss: ~0.5 kg/week.
Example 2: Lean bulk, 25M, very active, TDEE 3,100 kcal.
Surplus: +350 kcal. Daily intake = 3,100 + 350 = 3,450 kcal/day. Expected gain: ~0.15 kg muscle/week with training.
Example 3: Slow cut, 40M, moderately active, TDEE 2,400 kcal.
Target deficit: −250 kcal. Daily intake = 2,400 − 250 = 2,150 kcal/day. Expected loss: ~0.25 kg/week with less hunger.
Frequently Asked Questions
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It depends on your starting point and how quickly you want to lose fat. A 500 kcal/day deficit is a safe, widely recommended starting point for most people. Larger deficits (700–1,000 kcal) are sometimes used for shorter periods but increase the risk of muscle loss and rebound. A deficit larger than 1,000 kcal/day is not recommended without medical supervision.
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Several things can cause a plateau: your TDEE has decreased as your body weight dropped; you've reduced NEAT (unconscious daily movement) in response to eating less; your calorie tracking has become less accurate over time; or you're retaining water (which can mask fat loss on the scale). Recalculate your TDEE at your current weight, tighten tracking, and be patient — the scale often shows losses in steps rather than a straight line.
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Large, sustained deficits (> 1,000 kcal/day) can cause muscle loss, nutrient deficiencies, gallstones, hormonal disruption, and metabolic adaptation. Very low calorie diets (< 800 kcal/day) should only be used under medical supervision. For most people, a moderate deficit (250–500 kcal/day) is safer and produces better long-term results.
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This depends on how you calculated your TDEE. If you used an activity multiplier that accounts for your exercise, those calories are already included in your TDEE and you should not eat them back. If you used a sedentary TDEE and plan to add exercise on top, then eating back a portion (50–75%) of exercise calories is reasonable.
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Approximately 7,700 kcal per kilogram (about 3,500 kcal per pound). This means a 500 kcal/day deficit creates a weekly deficit of 3,500 kcal, which is roughly equivalent to losing 0.5 kg of fat per week. In practice, early weight loss also includes water and glycogen losses, so the initial rate may be faster.
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Recalculate every 4–6 weeks, or whenever your weight changes by more than 4–5 kg. Your TDEE decreases as your body weight decreases, so eating the same number of calories will gradually produce a smaller and smaller deficit over time.