Free Tool
Calorie Deficit Calculator
Find out exactly how many calories to eat each day to lose weight at the pace you want — without starving yourself.
Calorie Deficit Calculator
Sex
Daily Calorie Target
2083
2633 Your TDEE
3850 Weekly Deficit (kcal)
Mifflin-St Jeor + Activity Factor
TDEE = BMR × activity factor − daily deficit A calorie deficit is when you consume fewer calories than your body burns in a day. This calculator uses your Basal Metabolic Rate (BMR), activity level, and weight loss goal to give you a personalized daily calorie target that creates a safe, sustainable deficit. The standard rule is that 7,700 kcal of deficit equals approximately 1 kg of body fat.
How to Use This Calculator
1
Select your sex — the formula accounts for differences in body composition between men and women.
2
Enter your age, weight in kilograms, and height in centimeters.
3
Choose your activity level from the dropdown. Be honest — most people overestimate how active they are.
4
Select your weekly weight loss goal. 0.5 kg/week is the most sustainable pace for most people.
5
Your daily calorie target updates instantly.
How the Calorie Deficit Works
Your body needs a minimum number of calories just to stay alive (BMR). On top of that, physical activity burns additional calories. Together, these make up your Total Daily Energy Expenditure (TDEE) — the number of calories you actually burn each day.
To lose fat, you need to eat less than your TDEE. The difference between what you eat and what you burn is your calorie deficit. This calculator subtracts a daily deficit from your TDEE based on your chosen weekly weight loss goal.
The 7,700 kcal Rule
One kilogram of body fat contains roughly 7,700 kilocalories of stored energy. To lose 0.5 kg per week, you need a deficit of approximately 550 kcal per day. To lose 1 kg per week, you need about 1,100 kcal per day below your TDEE.
Note: Deficits larger than 1,000 kcal/day are generally not recommended as they can lead to muscle loss, nutrient deficiencies, and metabolic adaptation.
Activity Level: Why It Matters
Your activity multiplier makes a huge difference. A sedentary person burns about 20% fewer calories than a moderately active person of the same height, weight, and age. If you overestimate your activity level, your calorie target will be too high and you won’t see results. Start conservative and adjust based on actual progress.
Why We Use Mifflin-St Jeor
This calculator uses the Mifflin-St Jeor equation for BMR, which is the most validated formula for the general population. It was developed in 1990 and is the equation recommended by major nutrition authorities. While no formula is perfect for every individual, it provides the most reliable starting point for most people.
Calorie Deficit Planning for Personal Trainers
As a personal trainer, calorie targets are one of the most important — and most misused — tools in your toolkit. This calculator gives you a solid baseline for client nutrition conversations. Pair it with body composition tracking and regular check-ins to fine-tune targets over time.
With Gymkee, you can build personalized meal plans and track client nutrition progress alongside their training — everything in one app that your clients actually open.
Frequently Asked Questions
How big should my calorie deficit be?
For most people, a deficit of 300–550 kcal/day (targeting 0.25–0.5 kg/week loss) is optimal. This is large enough to see consistent progress but small enough to preserve muscle mass, energy levels, and long-term adherence.
What happens if my calorie deficit is too large?
Deficits above 1,000 kcal/day often backfire. Your body adapts by lowering your metabolic rate, breaking down muscle for energy, and increasing hunger hormones. You may lose weight faster initially, but it’s harder to sustain and more likely to result in rebound weight gain.
Should I eat back calories burned from exercise?
This calculator already factors in your activity level through the TDEE multiplier. If you selected your activity level correctly, your exercise calories are already included. Eating them back on top would reduce your deficit. However, if you exercise significantly more than your selected level on a given day, a small top-up is reasonable.
Why does the calculator set a minimum of 1,200 kcal?
Eating below 1,200 kcal/day (for most adults) makes it nearly impossible to meet essential micronutrient needs and is associated with metabolic slowdown, muscle loss, and nutrient deficiencies. This calculator enforces a 1,200 kcal floor as a safety guardrail.
How do I know if my activity level is right?
Sedentary means little to no exercise and a desk job. Lightly active means 1–3 light workouts per week. Moderately active means 3–5 workouts per week with moderate intensity. Very active means 6–7 hard workouts per week. Extremely active means multiple workouts per day or a very physically demanding job.
How often should I recalculate my calorie target?
Recalculate every 4–6 weeks or whenever your weight changes by 3–5 kg. As you lose weight, your BMR decreases, which means your deficit gradually shrinks unless you update your numbers.
Help Your Clients Hit Their Calorie Targets
Gymkee gives personal trainers the tools to create personalized meal plans, track client nutrition, and deliver real results.
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