This calorie calculator estimates how many calories you should eat per day to maintain your current weight, and how to adjust that number to lose or gain weight at a safe, sustainable pace. It uses the Mifflin-St Jeor equation — the formula the American Dietetic Association found most accurate for estimating resting energy needs — combined with a multiplier for your activity level.
Enter your age, gender, height, weight, and how active you are, and you will get your maintenance calories plus ready-made daily targets for mild weight loss, standard weight loss, and weight gain. Your calorie needs change as your body changes, so recalculate every 10–15 pounds of progress.
How Daily Calorie Needs Are Calculated
The calculator starts with your basal metabolic rate (BMR) — the energy your body burns at complete rest — using the Mifflin-St Jeor equation:
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
BMR is then multiplied by an activity factor to get your total daily energy expenditure (TDEE), which equals your maintenance calories:
- Sedentary (little or no exercise): × 1.2
- Light exercise 1–3 times/week: × 1.375
- Moderate exercise 4–5 times/week: × 1.465
- Active (daily exercise): × 1.55
- Very active (intense exercise 6–7 times/week): × 1.725
- Extra active (physical job plus training): × 1.9
Eating at maintenance keeps your weight stable; eating above or below it shifts your weight over time.
Picking a Safe Calorie Target
One pound of body fat stores roughly 3,500 calories, so a consistent daily deficit translates into predictable weekly change:
- −250 calories/day ≈ 0.5 lb lost per week (easiest to sustain)
- −500 calories/day ≈ 1 lb lost per week (the most common target)
- −1,000 calories/day ≈ 2 lb lost per week (aggressive — use only short term)
- +250 to +500 calories/day for gradual, mostly-lean weight gain
Most adults should not eat below about 1,200 calories/day (women) or 1,500 calories/day (men) without medical supervision — very low intakes make it hard to meet protein, vitamin, and mineral needs and accelerate muscle loss. Slower deficits paired with adequate protein (about 0.7–1 g per pound of body weight) and resistance training preserve far more lean mass than crash dieting.
Example: 30-Year-Old Male, 5'10", 165 lbs
Convert to metric: 165 lbs ÷ 2.2046 = 74.8 kg, and 70 inches × 2.54 = 177.8 cm.
BMR = 10 × 74.8 + 6.25 × 177.8 − 5 × 30 + 5 = 1,715 calories/day.
With moderate exercise 4–5 times a week (multiplier 1.465), maintenance is 1,715 × 1.465 ≈ 2,512 calories/day. His targets become:
- Mild weight loss: 2,262 calories/day (−0.5 lb/week)
- Weight loss: 2,012 calories/day (−1 lb/week)
- Mild weight gain: 2,762 calories/day (+0.5 lb/week)
After losing 10–15 pounds he should re-run the numbers, because a lighter body burns fewer calories at rest and during activity.
Frequently Asked Questions
How many calories should I eat a day?
Most adult women need roughly 1,600–2,400 calories per day and most adult men need 2,000–3,000, according to U.S. Dietary Guidelines. Your exact number depends on age, height, weight, and activity level — this calculator estimates it with the Mifflin-St Jeor equation, then you subtract 250–500 calories to lose weight or add 250–500 to gain.
How many calories should I eat to lose weight?
Eat about 500 calories below your maintenance level to lose roughly 1 pound per week. For someone maintaining on 2,500 calories, that means a 2,000-calorie target. A smaller 250-calorie deficit produces slower loss (about 0.5 lb/week) but is easier to stick with long term.
Is a 1,200-calorie diet safe?
For most women, 1,200 calories per day is considered the minimum for meeting basic nutrient needs; for men the floor is about 1,500. Eating below these levels without medical supervision risks nutrient deficiencies, muscle loss, fatigue, and a rebound in appetite. If this calculator suggests fewer than 1,200 calories, choose a slower rate of loss instead.
Should I eat back the calories I burn exercising?
Usually not — your activity level multiplier already accounts for regular exercise. Only add calories back if you selected "sedentary" and then did a workout the calculator did not account for. Fitness trackers commonly overestimate exercise burn by 20–90%, so eating back every tracked calorie often erases the deficit.
Why did my weight loss stall even though I kept the same calories?
As you lose weight, your body burns fewer calories at rest and during movement, so your original deficit shrinks. A 15–20 lb loss can lower daily needs by 100–200 calories. Recalculate your targets every 10–15 pounds, and expect normal week-to-week fluctuations of 1–3 lbs from water and food weight.