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Calorie Deficit Calculator
Daily calories to lose weight at your chosen pace, how long it takes to reach your goal weight and a safe-minimum check.
Calculated in your browser – nothing you enter is sent or stored.
A calorie deficit means eating fewer calories than your body burns, so it uses stored fat for the difference. This calorie deficit calculator finds your maintenance calories, the daily calorie target for losing 0.5 to 2 pounds a week, and when you could reach your goal weight – and it warns you if a target is too low to be safe.
How to Use the Calorie Deficit Calculator
- Enter your age, sex, height and weight, and pick the activity level that matches a normal week.
- Enter your goal weight in the same unit as your current weight.
- Choose a pace. 1 pound a week is a common, sustainable target.
How the Deficit Is Calculated
- BMR (calories at rest) with the Mifflin-St Jeor equation: 10 × kg + 6.25 × cm − 5 × age, then +5 for men or −161 for women.
- Maintenance calories (TDEE) = BMR × activity factor (1.2 sedentary to 1.9 extra active).
- Daily deficit = pounds per week × 3,500 ÷ 7. One pound a week is about 500 calories a day.
- Calorie target = TDEE − deficit.
Example: a 35-year-old woman, 5 ft 9 in and 170 lb, who exercises 1–3 days a week has a BMR of about 1,530 and maintenance calories of about 2,104. To lose 1 lb a week she would eat about 1,604 calories a day and reach a goal of 150 lb in roughly 20 weeks.
| Pace | Daily deficit | Calories a day | Time to lose 20 lb |
|---|---|---|---|
| 0.5 lb/week | 250 | 1,854 | 40 weeks |
| 1 lb/week | 500 | 1,604 | 20 weeks |
| 1.5 lb/week | 750 | 1,354 | 13.3 weeks |
| 2 lb/week | 1,000 | 1,104 ⚠ | 10 weeks |
At 2 lb a week her target falls below 1,200 calories, the usual minimum for women without medical supervision (about 1,500 for men). A slower pace or more activity is the safer way to get there.
Is the 3,500-Calorie Rule Accurate?
It is a good starting estimate, but weight loss usually slows over time. As you get lighter you burn fewer calories, and your body adapts a little. The NIH Body Weight Planner models this in detail. In practice, recheck your numbers every 10–15 pounds and expect the goal date to move a few weeks later than the simple estimate.
Tips for a Sustainable Deficit
- Aim for 1–2 lb a week at most. Faster loss tends to cost muscle and is harder to keep off.
- Keep protein high – it keeps you fuller and protects muscle. The macro calculator shows how many grams to eat.
- Add strength training two or three times a week.
- Track honestly for a few weeks: drinks, oils and snacks add up.
- Watch the trend, not daily weigh-ins, which swing with water and salt.
Sources
- NIH NIDDK – Body Weight Planner
- CDC – Steps for losing weight
- Dietary Guidelines for Americans, 2020–2025 – Estimated calorie needs
Last reviewed: October 2026 by the ShrinkBee team. Calorie targets are estimates for healthy adults and are not medical advice. Talk to your doctor before a weight-loss plan if you are pregnant, nursing or have a health condition.
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