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Calorie Deficit Calculator

A calorie deficit is the engine of weight loss. Enter your stats to find your maintenance calories and exactly how much to eat each day to lose weight at your chosen pace.

Built and reviewed by Jesse · Last reviewed

Fill in your details to see your calorie deficit targets.

  1. Enter your stats and activity level. These set your maintenance calories (TDEE).
  2. Choose a weight-loss pace. From gentle to aggressive; the calculator applies a general lower-intake guardrail.
  3. Read your daily calorie target. Eat at this level to lose weight at the pace you chose.

Every day your body burns a certain number of calories — your Total Daily Energy Expenditure (TDEE). Eat that many and your weight stays stable. Eat fewer, and your body covers the gap by burning stored energy, mostly fat. That gap is your calorie deficit.

The size of the deficit sets your pace. Because a kilogram of body weight stores roughly 7,700 calories (about 3,500 per pound), a 500-calorie daily deficit adds up to roughly 0.45 kg (1 lb) of loss per week. This calculator finds your maintenance level first, then shows the daily intake for several sustainable paces.

  1. Enter your sex, age, height, and weight.
  2. Pick the activity level that matches your typical week (be honest — most people overestimate).
  3. Optionally enter how much weight you want to lose to see an estimated timeline for each pace.
  4. Compare the paces and pick a daily calorie target you can realistically stick to. Slower and consistent beats fast and abandoned.

A good rule of thumb is to aim to lose about 0.5–1% of your body weight per week. Faster than that and you risk losing muscle alongside fat, feeling constantly hungry, and burning out. Slower paces are easier to maintain and protect your training performance.

Keep protein high (around 1.6–2.2 g per kg of body weight) and include resistance training. Both signal your body to hold onto muscle so more of the weight you lose is fat. See the macro calculator to turn your target calories into daily protein, carb, and fat goals.

  • Cutting too hard, too fast. A crash deficit burns muscle and rarely lasts. Pick a pace you could hold for months.
  • Not tracking accurately. Untracked oils, drinks, and bites easily add 200–400 calories a day and erase a moderate deficit.
  • Never recalculating. Your maintenance drops as you get lighter. Recompute every 5–10 kg (10–20 lb) so your target stays honest.
  • Chasing the daily scale. Water weight swings hide fat loss. Judge progress by the 2–3 week trend, not day to day.

Calorie deficit and weight loss

target = TDEE - daily deficit
weekly loss(kg) ~= (daily deficit x 7) / 7700
TDEE
= maintenance calories (Mifflin-St Jeor BMR x activity factor)
7700
= approximate calories stored per kilogram of body fat (3500 per pound)

A 500-calorie daily deficit is roughly 0.45 kg (1 lb) of loss per week.

What is a calorie deficit?

A calorie deficit means eating fewer calories than your body burns in a day (your TDEE). When you're in a deficit, your body makes up the difference by using stored energy — mostly body fat — which is how weight loss happens.

How big should my calorie deficit be?

For most people, a deficit of 300–750 calories per day is the sweet spot — fast enough to see steady progress (about 0.25–0.75 kg or 0.5–1.5 lb per week) but small enough to preserve muscle and stay consistent. Larger deficits work faster but are harder to sustain and raise the risk of muscle loss and fatigue.

How many calories should I eat to lose 1 kg (or 2 lb) per week?

One kilogram of body weight is roughly 7,700 calories (a pound is about 3,500). Losing 1 kg per week requires an average deficit of about 1,100 calories per day, and 2 lb per week needs about 1,000 per day. These are aggressive targets — the calculator applies a general lower-intake guardrail, but that does not make every displayed target appropriate for every person.

Why does the calculator use a lower-intake guardrail?

Very low calorie targets can make it harder to meet protein and micronutrient needs. The calculator uses commonly cited planning floors of 1,500 calories for men and 1,200 for women, but these are not individualized medical safety thresholds. Your appropriate intake depends on your size, health, activity, and other circumstances.

Will a calorie deficit slow my metabolism?

Your metabolism adapts modestly during weight loss — you burn a bit less as you get lighter and your body becomes more efficient. This is normal and manageable: recalculate your maintenance every 5–10 kg (10–20 lb) lost, keep protein high, and include resistance training to protect muscle and keep your metabolic rate up.

Why am I not losing weight in a deficit?

The most common reasons are underestimating intake (untracked bites, oils, drinks), overestimating activity, and water-weight fluctuations masking real fat loss. Track your intake carefully for two weeks and weigh yourself under consistent conditions. If the scale trend is truly flat over 2–3 weeks, reduce your target by 100–200 calories.

Should I do cardio or just eat less?

You can create a deficit through diet, activity, or both. Diet is the most reliable lever because it's easier to control, but adding activity lets you eat more while staying in a deficit and has independent health benefits. A combination is usually the most sustainable approach.

Is a calorie deficit safe for everyone?

For healthy adults, a moderate deficit is safe. But if you're pregnant or breastfeeding, under 18, have a history of disordered eating, or a medical condition, talk to a doctor or registered dietitian before cutting calories. This calculator provides general estimates, not medical advice.

References

FitCalcs calculators provide general estimates for healthy adults and are not medical advice.

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