Calorie Deficit Calculator
Find your daily calorie target to lose weight at a safe, sustainable pace. This calculator uses your BMR, activity level, and goal weight to give you an exact deficit target — plus a realistic timeline so you know what to actually expect.
Enter your details
Your deficit is calculated from your Total Daily Energy Expenditure (TDEE) — the calories you actually burn each day based on your body and activity level. Eat below that number and you lose weight.
Safe deficit range
Most nutrition guidelines recommend a deficit of 250–1,000 calories/day. Above 1,000 cal/day increases risk of muscle loss and nutrient deficiency.
About the formula
Uses Mifflin-St Jeor to calculate BMR, then multiplies by your activity factor to get TDEE. Subtracts your chosen deficit to give a daily calorie target.
What is a calorie deficit?
A calorie deficit happens when you consume fewer calories than your body burns in a day. Your body then draws on stored fat for the extra energy it needs — which is how weight loss occurs.
The size of your deficit determines how fast you lose weight. A larger deficit means faster results but also more hunger, more muscle loss risk, and less sustainability. A moderate deficit of 300–500 calories per day is considered the sweet spot for most people.
Calorie deficit formula
This calculator uses a 3-step process:
How to use this calorie deficit calculator
- Choose your unit system — imperial (lb, ft) or metric (kg, cm).
- Enter your age, biological sex, height, and current weight.
- Enter your goal weight — what you want to reach.
- Select your activity level as honestly as possible. Most people are sedentary or lightly active.
- Choose your weight loss pace — moderate (1 lb/week) is sustainable for most people.
- Click Calculate to see your daily calorie target and timeline.
Activity level guide
Choosing the right activity level is the most important input — overestimating it is the most common mistake:
When in doubt, choose one level lower than you think. It is easier to eat a little more if you are losing too fast than to stall because you overestimated your burn.
Example calculation
A 32-year-old male, 5'9" (175 cm), 185 lb (84 kg), lightly active, wants to reach 165 lb (75 kg) at 1 lb per week:
This person eats 1,946 calories per day, loses about 1 lb per week, and reaches their goal in roughly 5 months — a realistic and sustainable outcome.
Why your timeline might vary
The calculator gives a mathematical estimate. Real weight loss is not perfectly linear because:
- Water weight: The first 1–2 weeks often show faster loss due to water, not fat.
- Metabolic adaptation: Your body gradually burns slightly fewer calories as you lose weight.
- Muscle vs fat: Exercise preserves muscle, which weighs more than fat. The scale may move slower even as your body composition improves.
- Consistency: Days over target slow the average. Days under target speed it up.
Treat the timeline as a guide, not a deadline. Consistent effort over time matters far more than hitting the exact date.
Frequently asked questions
How many calories should I cut to lose 1 pound per week?
A deficit of approximately 500 calories per day results in about 1 pound of weight loss per week, since 1 lb of fat contains roughly 3,500 calories. This is generally considered a safe and sustainable rate for most adults.
What is the minimum number of calories I should eat?
Most guidelines recommend no less than 1,200 calories per day for women and 1,500 for men, even when trying to lose weight quickly. Going below these thresholds increases the risk of nutrient deficiency, muscle loss, and metabolic adaptation.
Should I eat back calories burned through exercise?
If you chose an accurate activity level, your exercise calories are already factored into your TDEE. Eating them back on top of your target would erase the deficit. Only eat back exercise calories if you chose a lower activity level than your actual routine.
Why am I not losing weight despite being in a deficit?
The most common reasons are overestimating activity level, underestimating food intake, water retention (especially around menstruation or after high-sodium meals), or not giving it enough time — weight fluctuates daily by 1–4 lbs. Track over 2–4 weeks before drawing conclusions.
Is a larger deficit better for faster results?
A larger deficit does accelerate weight loss on paper, but deficits above 1,000 calories per day significantly increase muscle loss, hunger, and the likelihood of giving up. For most people, 1 lb per week is the sustainable upper limit for fat-focused loss.
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Disclaimer
This calorie deficit calculator is for educational and informational purposes only. Calorie targets are estimates based on population-level formulas and do not account for individual medical conditions, medications, or metabolic differences. Consult a registered dietitian or qualified healthcare professional before making significant changes to your diet.