Calculate your calorie deficit
Enter your details. The calculator estimates BMR with the Mifflin-St Jeor equation, multiplies by activity to get TDEE, then applies your chosen deficit.
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What is a calorie deficit?
A calorie deficit means eating fewer calories than your body uses over time. Your TDEE (total daily energy expenditure) covers your whole day: resting energy use, movement, exercise, and digesting food. The deficit is the gap between that amount and what you eat:
Daily intake target = TDEE − daily deficit
For example, a TDEE of 2,400 kcal with a 400 kcal deficit gives an intake target of 2,000 kcal a day. The result of this calculator already has the deficit taken out — use the target as the amount to eat; you do not need to subtract anything more.
How the calculation works
1. Your BMR (calories burned at complete rest) is estimated with the Mifflin-St Jeor equation from age, sex, weight and height. 2. An activity multiplier (1.2–1.9) turns BMR into TDEE. 3. Your deficit is applied — either a percentage of TDEE, or a daily deficit sized from your target loss rate using about 7,700 kcal per kilogram of body fat (about 3,500 kcal per pound). 4. The target calories are split into protein (30%), carbohydrates (40%) and fat (30%).
Worked arithmetic
A 30-year-old man, 80 kg, 180 cm, moderately active, choosing a moderate 20% deficit:
- BMR: 10×80 + 6.25×180 − 5×30 + 5 = 1,780 kcal
- TDEE: 1,780 × 1.55 = 2,759 kcal
- Deficit: 2,759 × 20% = 552 kcal/day
- Daily target: 2,759 − 552 = 2,207 kcal/day
- Expected loss: 552 × 7 ÷ 7,700 = 0.50 kg/week
- Macros: protein 2,207 × 30% ÷ 4 = 166 g; carbs 2,207 × 40% ÷ 4 = 221 g; fat 2,207 × 30% ÷ 9 = 74 g
Deficit sizes at a glance
| Deficit | Size | Typical loss rate |
|---|---|---|
| Mild | 10% of TDEE | About 0.25 kg/week |
| Moderate | 20% of TDEE | About 0.5 kg/week |
| Aggressive | 25% of TDEE | About 0.5–1 kg/week |
Note: Very low calorie targets are not for everyone. If your target lands below about 1,200 kcal, talk to a doctor or registered dietitian before proceeding. Some fat-loss models also note that body fat can only release energy at a limited rate, so extremely aggressive deficits risk muscle loss rather than faster fat loss.
Calories in Common Foods
Use this reference to estimate what your calorie target actually looks like on a plate. Values are approximate, based on USDA data.
| Food | Calories (approx.) | Why it fits a calorie deficit |
|---|---|---|
| Medium banana | ~105 kcal | An easy pre-portioned snack — far more filling than a 100 kcal processed snack. |
| Medium apple | ~95 kcal | Fiber and chewing time make apples one of the most filling fruits per calorie. |
| Whole avocado | ~240 kcal | Nutrient-dense but calorie-dense — half an avocado (about 120 kcal) gives creamy satiety for much less. |
| Large egg | ~70 kcal | A lot of protein for very few calories, which keeps hunger down between meals. |
| Greek yogurt, plain | ~59 kcal per 100 g | About double the protein of regular yogurt at barely more calories — a 200 g bowl is about 118 kcal. |
| Chicken breast, cooked | ~165 kcal per 100 g | The classic deficit protein: about 31 g of protein for 165 kcal keeps muscle while you lose. |
| Cooked white rice | ~130 kcal per 100 g | A filling staple — weigh it cooked; a 150 g serving is about 195 kcal. |
| White bread, 1 slice | ~75 kcal | Fits a deficit as long as you count the slices; open-faced sandwiches halve the cost. |
| Almonds | ~579 kcal per 100 g (~164 kcal per 28 g handful) | A healthy fat source, but easy to overeat — stick to a pre-counted 28 g handful. |
| Olive oil | ~119 kcal per tablespoon | The silent calorie leak in most diets — measure it, since a free pour can be 2–3 times this. |
Calorie Food FAQs
How many calories are in a banana? A medium banana has about 105 kcal — a useful pre-portioned snack that fits almost any calorie deficit.
How many calories are in an egg? A large egg has about 70 kcal, making eggs one of the most protein-rich foods per calorie — ideal breakfast material in a deficit.
Is avocado good for a calorie deficit? A whole avocado has about 240 kcal, so it is not a low-calorie food. But half an avocado (about 120 kcal) adds fiber and healthy fat that keep you full — it works in a deficit as long as you count it.
What foods are low in calories but filling? Eggs (about 70 kcal), plain Greek yogurt (about 59 kcal per 100 g), apples (about 95 kcal), and chicken breast (about 165 kcal per 100 g) combine protein or fiber with few calories — the combination that fights hunger best.
How many almonds can I eat in a calorie deficit? Almonds have about 579 kcal per 100 g, so a small 28 g handful is roughly 164 kcal. That fits a deficit fine — just weigh or count it rather than eating from the bag.
How much protein do I need while losing weight? Around 1.6 to 2.2 g per kg of body weight per day helps protect muscle in a deficit. Use the protein calculator to get your exact number.
Understanding your results
What your projected weekly loss rate generally indicates:
| Weekly rate | Category | What it means |
|---|---|---|
| 0 – 0.25 kg/week | Mild deficit | Slow and easy to sustain; muscle-sparing |
| 0.25 – 0.5 kg/week | Moderate deficit | The most commonly recommended pace — steady and sustainable |
| 0.5 – 1.0 kg/week | Aggressive deficit | Faster results, but more hunger and a higher risk of muscle loss and fatigue |
| Above 1.0 kg/week | Extreme deficit | Not recommended without professional supervision |
Your estimated loss is an average, not a promise for every week. Water-weight swings can hide fat loss on the scale for days at a time, and your TDEE drops as you get lighter, so recalculate your targets every few weeks — the same inputs at a lower weight give a smaller target.
How long will it take to reach your goal?
Enter a goal weight above and the calculator estimates your timeline: the kilograms to lose divided by your estimated weekly loss. For example, losing 5 kg at a 500 kcal daily deficit is about 11 weeks (5 ÷ (500×7÷7,700)).
Two things to know: the math assumes a constant deficit — real progress slows as TDEE falls with body weight, and plateaus are normal — and exercise widens the deficit only by its net burn: an hour of activity burns the gross amount, but part of that energy would have been burned anyway at rest. The net portion is what actually adds to your deficit.
Related calculators
Macro Calculator — daily calories, protein, carbs and fat from your body, activity and goal.
Protein Calculator — how much protein you need per day, from body weight and activity.
TDEE Calculator — your total daily energy expenditure from BMR and activity level.
BMR Calculator — your basal metabolic rate, the calories burned at complete rest.
Lean Body Mass Calculator — your lean body mass in kg plus an estimated body fat percentage.
Body Fat Calculator — estimate your body fat percentage from simple body measurements.
Pace Calculator — running pace, race time and distance from any two of the three, in km or miles.
Diet Macro Presets — keto, low-carb, high-protein and balanced macro ratios turned into daily grams.
Best Macro Ratio for Weight Loss — guide to protein, ratios and adjusting your split in a deficit.
What Is IIFYM — explainer guide to "If It Fits Your Macros".
Macros 101 — beginner guide to protein, carbs and fat and how to start tracking.
How to Calculate Your Macros — step-by-step guide: BMR, TDEE, goal calories, protein, fat and carbs, with a worked example.
Frequently Asked Questions
How big a calorie deficit should I be in to lose weight? A common starting point is a 10–20% deficit below TDEE. A 20% deficit on a 2,500 kcal TDEE gives a 2,000 kcal daily target, usually a steady loss of about 0.5 kg per week.
How many calories are in 1 kg of body fat? About 7,700 kcal per kilogram (about 3,500 kcal per pound). A daily deficit of 500 kcal over a week — 3,500 kcal total — is roughly 0.45 kg of fat loss per week.
What is a safe rate of weight loss? Around 0.25 to 0.5 kg per week is a common guideline for steady, sustainable loss; up to about 1 kg per week is used for larger or more active people.
Do I need a protein target while in a deficit? Yes — protein matters even more in a deficit. Around 1.6 to 2.2 g per kg of body weight per day helps you keep muscle while losing weight.
Why am I not losing weight in a calorie deficit? Common reasons: the deficit is smaller than estimated (under-reported food intake or an over-estimated activity level), water-weight swings hiding fat loss on the scale, or your TDEE dropping as you got lighter. Recalculate your numbers and track for 2–3 weeks before changing anything.
Is this medical advice? No. This is general information only. Talk to a doctor or registered dietitian before changing your diet, especially if you are pregnant, have diabetes, kidney disease, or any health condition.