How to use the calorie calculator
- Choose Metric (cm, kg) or US units (ft, in, lb).
- Pick your sex and enter your age. The calculator is for adults aged 18 and over.
- Enter your height and weight.
- Choose the activity level that matches a typical week. If you're unsure, pick the lower one.
- Read your maintenance calories and the table of targets for losing or gaining weight.
How daily calories are calculated
The calculator first estimates your basal metabolic rate (BMR), the energy your body uses at complete rest, with the Mifflin-St Jeor equation. It then multiplies BMR by an activity factor to get your maintenance calories:
Mifflin-St Jeor (1990) is the equation the Academy of Nutrition and Dietetics found most accurate for healthy adults. It is usually within 10% of measured BMR. The targets rest on the rough rule that 3,500 kcal equals about 1 pound (0.45 kg) of body fat. A daily gap of 500 kcal is therefore about 1 pound a week.
Worked example
These are the calculator's defaults: a 35-year-old man, 175 cm, 70 kg, moderately active.
- BMR: 10 × 70 + 6.25 × 175 − 5 × 35 + 5 = 700 + 1,093.75 − 175 + 5 = 1,623.75, about 1,624 kcal
- Maintenance: 1,623.75 × 1.55 = 2,516.8, so 2,517 kcal a day
- Mild weight loss (−250): 2,267 kcal, about 0.5 lb a week
- Weight loss (−500): 2,017 kcal, about 1 lb a week
- Fast weight loss (−1,000): 1,517 kcal, about 2 lb a week, just above the 1,500 kcal minimum for men
- Weight gain (+500): 3,017 kcal
Safe minimums and realistic expectations
The calculator never suggests less than 1,200 kcal a day for women or 1,500 kcal a day for men. Below those levels it's hard to get enough protein, vitamins and minerals from food, and very low-calorie diets should only be followed under medical supervision. If a deficit would take you below the minimum, the table shows the minimum instead. When your maintenance is already close to it, the table suggests talking to a professional rather than eating less.
| Goal | Daily change | Approximate weekly change |
|---|---|---|
| Mild loss or gain | 250 kcal | 0.5 lb (0.23 kg) |
| Loss or gain | 500 kcal | 1 lb (0.45 kg) |
| Fast loss or gain | 1,000 kcal | 2 lb (0.91 kg) |
Real progress is rarely this tidy. Weight swings day to day with water and food, and as you lose weight your maintenance calories fall, so the same intake gives slower results over time. Recalculate every 4 to 5 kg (about 10 lb) of change. The CDC describes 1 to 2 pounds a week as a gradual, steady pace that's easier to sustain.
Frequently asked questions
How accurate is this calorie estimate?
For most healthy adults, Mifflin-St Jeor lands within about 10% of a lab measurement, but the activity factor adds more uncertainty. Treat the result as a starting point. Track your weight for 2 to 3 weeks and adjust by 100 to 200 kcal if it moves differently than expected.
Which activity level should I choose?
Count only planned exercise and physical work, not ordinary walking around the house. Most people with desk jobs who exercise a few times a week are lightly or moderately active. Overestimating activity is the most common reason the numbers don't match real results.
Why won't the calculator go below 1,200 or 1,500 calories?
Very low intakes make it hard to meet nutrient needs and can cause muscle loss, fatigue and gallstones. Diets below these levels should only be followed with a doctor or registered dietitian. Choose a smaller deficit, or add activity instead.
Should I eat back the calories I burn exercising?
If you chose an activity level that includes your workouts, those calories are already counted. Adding them again would double-count them. Fitness trackers also tend to overestimate the calories burned in exercise.
Related calculators
- TDEE Calculator — Total daily energy expenditure: your BMR multiplied by your activity level, with every level side by side.
- BMR Calculator — Your basal metabolic rate from the Mifflin-St Jeor, revised Harris-Benedict and Katch-McArdle equations.
- Macro Calculator — Split your daily calories into grams of protein, carbs and fat, with preset or custom percentages and grams per meal.
- Healthy Weight Calculator — The healthy weight range for your height, where your weight sits, and how far you are from the range.
Results are estimates for general information and are not medical advice. Talk to a doctor or other qualified professional about your health. See our disclaimer.