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Calorie deficit calculator: find your daily calorie target
Your TDEE is the number of calories your body burns each day. Eating below it loses fat; eating above it gains weight. Find your number in seconds.
Calorie deficit calculator
Your result
Expected fat loss: 0.45 kg/week — track your average weight over two weeks and adjust by 100–150 kcal if needed.
About this tool
What a calorie deficit is — and why it matters
Your TDEE (Total Daily Energy Expenditure) is the number of calories your body burns in an average day. Eating below that creates a deficit — the mechanism behind fat loss. Eating above it creates a surplus — the mechanism behind weight gain.
This calculator estimates your TDEE from the Mifflin-St Jeor equation, then applies safe, evidence-based adjustments: a 500 kcal daily deficit produces roughly 0.5 kg of fat loss per week, which most research treats as the upper limit of sustainable progress.
Step by step
How to use the calorie deficit calculator
- 1
Enter your sex, age, height and weight
These four numbers calculate your BMR using the Mifflin-St Jeor equation.
- 2
Choose your activity level honestly
Overestimating it is the most common mistake — two gym sessions a week is usually lightly active, not very active.
- 3
Pick your goal (cut, maintain, or build)
Each option shows the kcal/day adjustment and expected weekly weight change.
- 4
Your daily calorie target appears instantly
Adjust intake by 100–150 kcal every two weeks based on real-world results.
Methodology
The formula behind your result
TDEE = BMR × activity multiplier
Target = TDEE + adjustment
| Goal | Adjustment (kcal/day) | Expected weekly change |
|---|---|---|
| Aggressive cut | -750 | ~0.75 kg/week loss |
| Moderate cut | -500 | ~0.5 kg/week loss |
| Mild cut | -250 | ~0.25 kg/week loss |
| Maintain weight | 0 | |
| Mild surplus | +250 | ~0.25 kg/week gain |
| Moderate surplus | +500 | ~0.5 kg/week gain |
Worked example
Example calculation
A moderately active woman, 30 years old, 165 cm, 68 kg. BMR ≈ 1,452 kcal; TDEE ≈ 2,250 kcal. On a moderate cut (−500 kcal): target = 1,750 kcal/day, expected fat loss ~0.5 kg/week.
Be aware
Assumptions and limitations
- TDEE estimates have ±10–15% individual variation — use as a starting point, track real results over 2 weeks, then adjust.
- Minimum intake of 1,200 kcal/day is enforced — going lower without medical supervision risks nutrient deficiency.
- Does not account for metabolic adaptation with prolonged dieting.
- Not suitable for pregnancy, under-18, or active eating disorder recovery.
Questions
Frequently asked questions
How big a deficit should I use?
A 500 kcal daily deficit (about 0.5 kg/week) is the most studied and most commonly recommended rate for fat loss with minimal muscle loss. Larger deficits produce faster short-term results but increase hunger, muscle catabolism and metabolic slowdown.
Why is there a 1,200 kcal floor?
Below roughly 1,200 kcal for women and 1,500 kcal for men, it becomes difficult to hit minimum protein, vitamin and mineral targets from food alone. The calculator won't set a target below 1,200 kcal regardless of the chosen deficit.
What if my results don't match the calculator?
Real-world weight loss rarely matches a formula exactly. Track your average weight over two weeks (daily weigh-ins, same conditions). If the trend doesn't match, adjust intake by 100–150 kcal and re-measure.
Should I eat back exercise calories?
This calculator already accounts for exercise through the activity multiplier. Don't add exercise calories on top unless you picked a lower activity level than your actual lifestyle.
How many calories do I need to cut to lose 1 kg per week?
One kilogram of body fat contains roughly 7,700 kcal. To lose 1 kg per week you would need a daily deficit of about 1,100 kcal — which is larger than most people can sustain without significant muscle loss and hunger. A more realistic target is 0.5 kg per week (550 kcal daily deficit). Most evidence-based guidelines treat 0.5–1 kg per week as the safe maximum for fat loss.
What happens if I eat too little on a calorie deficit?
Eating too far below your TDEE (typically more than 1,000 kcal below, or under 1,200 kcal total) risks muscle catabolism (your body breaking down muscle for energy), nutrient deficiencies, hormonal disruption, and metabolic adaptation — where your body reduces its calorie burn in response to restriction. This is why this calculator enforces a 1,200 kcal floor and why aggressive cuts are labelled as high-risk.
Is 1,200 calories too low?
For most adults, 1,200 kcal per day is at or below the minimum needed to meet basic nutrient requirements from food alone. Short-term, a very low calorie diet can work for supervised medical weight loss. Long-term, it typically leads to muscle loss, nutrient deficiency, and rebound weight gain. This calculator will not set a target below 1,200 kcal regardless of the deficit chosen.
How long will it take me to reach my goal weight?
A rough estimate: divide the total weight you want to lose by your expected weekly rate. At a 500 kcal daily deficit (roughly 0.5 kg/week), losing 10 kg would take approximately 20 weeks. In practice, weight loss slows over time as your TDEE decreases with lower body weight, so the real timeline is usually longer than a simple calculation suggests. Recalculate your TDEE and deficit every 4–6 weeks.
Estimates, not medical advice
FitnessCalculator.info provides general health information for educational purposes only and does not replace advice from a qualified doctor or registered dietitian.