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Calorie deficit calculator
For a moderate calorie deficit you eat 300 to 500 kcal less than you burn in a day. The calculator never goes below 1,200 kcal (women) or 1,500 kcal (men) and doesn’t work out a deficit for anyone under 18.
Your calorie deficit
Example: Woman, 35 years, 168 cm, 68 kg, lightly active, gentle
1,617 kcal a day. Gentle: 300 kcal below what you burn.
Split as in the app: 121 g protein, 162 g carbs, 54 g fat.
You burn: 1,917 kcal
Basal metabolic rate: 1,394 kcal
Moderate range: 1,417–1,617 kcal
Track your goal in the app
The SmarTasty app works out your daily goal with the same formulas and shows you in your diary what is left for the day. Free for iPhone and in the browser.
Pace (gentle: 300 kcal less, steady: 500 kcal less)
How active are you?
Hardly active (× 1.2): Sitting at work and at home, hardly any walking
Lightly active (× 1.375): Office job plus exercise 1–3× a week, or lots of walking
Active (× 1.55): On your feet a lot or exercise 3–5× a week
Very active (× 1.725): Physical work or exercise almost every day
The calculation runs in your browser. Your details are not saved and not sent anywhere.
300 or 500 kcal less: examples
This is the deficit for four example people. The calculator never goes below the floor: 1,200 kcal for women, 1,500 kcal for men.
Calories a day with a 300 and 500 kcal deficit, calculated with Mifflin-St Jeor
Example
Burned a day
300 kcal less
500 kcal less
Woman, 35 years, 168 cm, 68 kg, lightly active
1,917 kcal
1,617 kcal
1,417 kcal
Man, 42 years, 182 cm, 86 kg, active
2,779 kcal
2,479 kcal
2,279 kcal
Woman, 62 years, 160 cm, 58 kg, hardly active
1,331 kcal
1,200 kcal (floor)
1,200 kcal (floor)
Man, 28 years, 178 cm, 75 kg, very active
2,981 kcal
2,681 kcal
2,481 kcal
“Floor”: the calculator doesn’t go lower. How quickly your weight changes can’t be predicted reliably.
How the calculator works
First what you burn in a day: basal metabolic rate with Mifflin-St Jeor × activity factor, as in the calorie calculator.
Then 300 kcal (gentle) or 500 kcal (steady) less. These are the same two paces as in the app.
Floor: 1,200 kcal for women, 1,500 kcal for men, 1,350 kcal if you don’t give your sex. If the result is lower, the calculator shows the floor. With a BMI under 18.5 it doesn’t work out a deficit.
For comparison: the German S3 guideline on obesity names a deficit of about 500 to 600 kcal a day. The calculator stays at 300 to 500 kcal – smaller is easier for many people.
Example: Woman, 35 years, 168 cm, 68 kg, lightly active:
Burned a day 1,917 kcal, basal metabolic rate 1,394 kcal
300 to 500 kcal less = 1,417 to 1,617 kcal a day
Floor for women: 1,200 kcal – both values are above it
When not to use this calculator
In pregnancy and while breastfeeding.
Under 18.
If you have an eating disorder, even if it was a while ago.
If you have a medical condition such as diabetes, kidney or heart disease, and if you take medication regularly: please talk to your doctor first.
Very low-calorie diets belong under medical supervision.
If food and weight weigh heavily on you, talk to your GP or an eating disorder helpline.
Frequently asked questions
How many calories should I eat in a calorie deficit?
About 300 to 500 kcal less than your total energy expenditure. What that is in numbers depends on height, weight, age, sex and movement. That is exactly what the calculator above works out.
Where is the floor?
At 1,200 kcal for women and 1,500 kcal for men, or 1,350 kcal if you don’t give your sex. That is a common rule of thumb for diets without medical supervision. Under 18 and with a BMI under 18.5, the calculator doesn’t work out a deficit: then your body needs the energy. Very low-calorie diets belong under medical supervision.
Gentle or steady – which suits me?
With 300 kcal less, many people find it easier to stick with. 500 kcal less means going without more each day. Both are guide values, and you can switch at any time.
How quickly will my weight change?
That can’t be predicted reliably. Your weight goes up and down from day to day, for example because of water. Treat the result as a starting point and look at your weekly average after 2 to 4 weeks.
What if my weekly average doesn’t change?
Recalculate with your current weight or choose a lower activity level. Don’t go below the floor while you do.
Do I have to count calories?
Not necessarily. Regular meals with plenty of vegetables and a protein source make planning easier. If you want to know exactly, snap your food in the Food Diary and Photo Scan estimates the nutrition.
