Calorie Deficit Calculator

Use our free calorie deficit calculator to find exactly how many calories you should eat to lose weight. Enter your stats, pick a weight-loss pace, and you will get your daily calorie target, your deficit size, and a projected timeline to your goal weight.

Calculate Your Calorie Deficit

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What Is a Calorie Deficit?

A calorie deficit means eating fewer calories than your body burns in a day. To cover the gap, your body burns stored fat, which is how weight loss happens. A daily deficit of about 500 calories leads to roughly 0.5 kg of fat loss per week. For the full science, read our guide: What Is a Calorie Deficit?

How to Use This Calculator

  • Enter your age, gender, height, and current weight.
  • Select your activity level, from sedentary to extra active.
  • Pick a weight-loss pace: slow (0.25 kg/week), moderate (0.5 kg/week), fast (0.75 kg/week), or aggressive (1 kg/week).
  • Optionally enter your target weight to see a projected timeline.
  • Click Calculate My Deficit for your BMR, TDEE, daily deficit, and calorie target.

How the Math Works

First we estimate your basal metabolic rate (BMR) with the Mifflin-St Jeor equation, the formula researchers consider most accurate: BMR = 10 x weight(kg) + 6.25 x height(cm) – 5 x age + 5 for men, or – 161 for women. We multiply BMR by your activity factor to get your TDEE. Your deficit comes from the 7,700 kcal rule: one kilogram of body fat holds about 7,700 kcal, so losing 0.5 kg a week needs a daily deficit of 0.5 x 7,700 / 7 = 550 kcal. Your target is simply TDEE minus deficit.

Choosing Your Weight-Loss Pace

PaceWeekly lossDaily deficitBest for
Slow0.25 kg~275 kcalBeginners, or when you have little to lose
Moderate0.5 kg~550 kcalMost people (recommended)
Fast0.75 kg~825 kcalShort-term goals, experienced dieters
Aggressive1 kg~1,100 kcalHigher starting weight, ideally supervised

Moderate is the sweet spot for most people: fast enough to stay motivated, gentle enough to protect muscle and energy. Aggressive deficits work best for short periods and higher starting weights.

Example: Losing 0.5 kg Per Week

Take a 30-year-old man, 175 cm, 75 kg, moderately active. His BMR is 1,699 kcal/day and his TDEE is 2,633 kcal/day. At a moderate pace of 0.5 kg per week, his daily deficit is 550 kcal, so his target is 2,083 kcal/day. If his goal weight is 70 kg, he would get there in about 10 weeks. Try these exact numbers in the calculator above.

Tips for a Safe Calorie Deficit

  • Keep your target above your BMR and never below 1,200 kcal/day without medical supervision.
  • Eat enough protein: 1.6 to 2.2 g per kg of body weight protects muscle while you lose fat. Check our protein intake calculator for your number.
  • Lift weights 2 to 4 times a week. Strength training is what keeps the weight you lose as fat, not muscle.
  • Sleep 7 to 9 hours. Poor sleep raises hunger hormones and can stall fat loss even in a deficit.
  • Track honestly for two weeks before changing anything. Untracked snacks and drinks are the most common reason a deficit “stops working”.

Frequently Asked Questions

What is a good calorie deficit for weight loss?

A moderate deficit of about 500 kcal per day, which leads to roughly 0.5 kg of fat loss per week, works for most people. Research supports a deficit of 10 to 20 percent of your TDEE as the sweet spot between speed and sustainability.

How many calories are in one kilogram of body fat?

Roughly 7,700 kcal. That is why the math works out to about 550 kcal per day for half a kilo per week: 0.5 x 7,700 / 7.

How fast will I lose weight with a 500-calorie deficit?

About 0.5 kg per week, or around 2 kg per month, as long as you stay consistent. Water weight can make the first week look faster.

Is it safe to eat below my BMR?

Generally no. Your BMR is what your body burns at complete rest. Eating below it for extended periods can cause muscle loss, fatigue, hair loss, and nutrient deficiencies. Keep your target above BMR and above 1,200 kcal per day unless medically supervised.

Why am I not losing weight in a calorie deficit?

The most common causes are underestimating portions, untracked snacks, cooking oils and drinks, water retention masking fat loss, or an overestimated activity level. Track everything honestly for two weeks before adjusting your target.

Should I exercise while in a calorie deficit?

Yes. Strength training 2 to 4 times per week protects your muscle while you lose fat, which keeps your metabolism higher. Eating enough protein alongside it matters just as much.

What is the lowest I can safely cut my calories?

Most adults should not go below 1,200 kcal per day (women) or 1,500 kcal per day (men) without medical supervision. Very low targets also make the diet much harder to sustain.

How do I calculate my deficit without a calculator?

First find your TDEE with our TDEE calculator at https://healthcalculatorhub.com/tdee-calculator/, then subtract about 500 for roughly 0.5 kg of loss per week.

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