How to use the calorie calculator
- Choose US or metric units and enter your sex, age, height and current weight.
- Pick the activity level that describes a typical week. If you are between two levels, choose the lower one.
- Read your maintenance calories: the estimated intake that keeps your weight stable.
- Compare the daily targets for losing or gaining weight, and note any target flagged as very low.
- Check against reality. Weigh yourself regularly for a few weeks and adjust the target if your weight moves faster or slower than expected.
How the calculator estimates your calories
The calculation has two steps. First it estimates your basal metabolic rate (BMR), the calories your body burns at complete rest, with the Mifflin-St Jeor equation. The equation was published in 1990 from resting energy measurements (indirect calorimetry) of 498 healthy adults aged 19 to 78, both normal weight and obese. In that study, the older Harris-Benedict equations overestimated measured resting energy by about 5%.
BMR = 10 × W + 6.25 × H − 5 × A + s
- W
- weight in kilograms (pounds × 0.4536)
- H
- height in centimeters (inches × 2.54)
- A
- age in years
- s
- +5 for men, −161 for women
Second, it multiplies BMR by an activity factor to estimate your total daily energy expenditure (TDEE), which is your maintenance calories. The factors below are the multipliers most often paired with this equation. They are rules of thumb rather than measured values, so treat the result as a starting point.
| Activity level | Description | Multiplier |
|---|---|---|
| Sedentary | little or no exercise, desk job | × 1.2 |
| Lightly active | light exercise 1–3 days a week | × 1.375 |
| Moderately active | moderate exercise 3–5 days a week | × 1.55 |
| Very active | hard exercise 6–7 days a week | × 1.725 |
| Extra active | very hard exercise or a physical job | × 1.9 |
Worked example
Take a 35-year-old woman who is 5′ 5″ (165.1 cm) tall and weighs 150 lb (68 kg).
- BMR = 10 × 68.04 + 6.25 × 165.1 − 5 × 35 − 161 = 680.4 + 1,031.9 − 175 − 161 = 1,376 calories.
- She is moderately active, so TDEE = 1,376 × 1.55 = 2,133 calories a day.
- Subtracting 500 gives 1,633 calories a day. By the 3,500-calories-per-pound rule of thumb, 500 × 7 days = 3,500, or about 1 lb a week at first.
- Subtracting 1,000 gives 1,133, which is below the 1,200-calorie level the calculator flags for women.
Calories needed per day by age, sex and activity
The Dietary Guidelines for Americans publish estimated daily calorie needs for each age and sex group at three activity levels. They are based on the National Academies' Estimated Energy Requirement equations for a reference man 5 ft 10 in tall weighing 154 lb and a reference woman 5 ft 4 in tall weighing 126 lb, so people who are taller, heavier or more active will usually need more. The table below is for adults; it excludes pregnancy and breastfeeding.
| Age | Sedentary | Moderately active | Active |
|---|---|---|---|
| 19–20 | 2,600 | 2,800 | 3,000 |
| 21–25 | 2,400 | 2,800 | 3,000 |
| 26–30 | 2,400 | 2,600 | 3,000 |
| 31–35 | 2,400 | 2,600 | 3,000 |
| 36–40 | 2,400 | 2,600 | 2,800 |
| 41–45 | 2,200 | 2,600 | 2,800 |
| 46–50 | 2,200 | 2,400 | 2,800 |
| 51–55 | 2,200 | 2,400 | 2,800 |
| 56–60 | 2,200 | 2,400 | 2,600 |
| 61–65 | 2,000 | 2,400 | 2,600 |
| 66–70 | 2,000 | 2,200 | 2,600 |
| 71–75 | 2,000 | 2,200 | 2,600 |
| 76+ | 2,000 | 2,200 | 2,400 |
| Age | Sedentary | Moderately active | Active |
|---|---|---|---|
| 19–20 | 2,000 | 2,200 | 2,400 |
| 21–25 | 2,000 | 2,200 | 2,400 |
| 26–30 | 1,800 | 2,000 | 2,400 |
| 31–35 | 1,800 | 2,000 | 2,200 |
| 36–40 | 1,800 | 2,000 | 2,200 |
| 41–45 | 1,800 | 2,000 | 2,200 |
| 46–50 | 1,800 | 2,000 | 2,200 |
| 51–55 | 1,600 | 1,800 | 2,200 |
| 56–60 | 1,600 | 1,800 | 2,200 |
| 61–65 | 1,600 | 1,800 | 2,000 |
| 66–70 | 1,600 | 1,800 | 2,000 |
| 71–75 | 1,600 | 1,800 | 2,000 |
| 76+ | 1,600 | 1,800 | 2,000 |
In the guidelines, sedentary means only the activity of daily living; moderately active adds the equivalent of walking about 1.5 to 3 miles a day at 3 to 4 mph; active means walking more than 3 miles a day at that pace. For comparison, this calculator estimates 1,998 calories for a sedentary 30-year-old reference man and 1,532 for a sedentary 30-year-old reference woman, against the guidelines' 2,400 and 1,800. Different equations give different answers, which is a reminder that every figure here is an estimate.
Maintenance calories by weight
These estimates use this calculator's equation for a 35-year-old woman who is 5 ft 5 in and a 35-year-old man who is 5 ft 10 in. Each extra 10 lb adds about 45 calories to BMR before the activity multiplier.
| Weight | Woman: sedentary | Woman: moderate | Man: sedentary | Man: moderate |
|---|---|---|---|---|
| 130 lb | 1,543 | 1,993 | 1,837 | 2,373 |
| 150 lb | 1,652 | 2,133 | 1,946 | 2,514 |
| 170 lb | 1,760 | 2,274 | 2,055 | 2,654 |
| 190 lb | 1,869 | 2,414 | 2,164 | 2,795 |
| 210 lb | 1,978 | 2,555 | 2,273 | 2,935 |
| 230 lb | 2,087 | 2,696 | 2,381 | 3,076 |
| 250 lb | 2,196 | 2,836 | 2,490 | 3,217 |
How many calories to eat to lose weight
Weight loss requires eating fewer calories than you burn. The NHLBI's clinical guide for treating overweight and obesity in adults says that reducing intake by 500 to 1,000 calories a day will produce a weight loss of 1 to 2 pounds a week, and that faster rates do not lead to better long-term results. The mild, regular and extreme loss targets in this calculator correspond to cuts of 250, 500 and 1,000 calories a day.
The weekly rates shown come from the familiar rule that a pound of body weight holds about 3,500 calories. A 2013 analysis in the International Journal of Obesity compared that rule with carefully controlled weight-loss studies and found that it substantially overestimates actual weight loss. Expect progress to be slower than the rule predicts, and recalculate as your weight changes, since a lighter body burns fewer calories.
Is there a minimum safe calorie intake?
No single cutoff applies to everyone. The NHLBI clinical guide describes low-calorie diets of 1,000 to 1,200 calories a day for most women and 1,200 to 1,600 for men, and says a diet should not go below 800 calories a day. To stay on the cautious side, this calculator marks any weight-loss target below 1,200 calories for women or 1,500 for men and suggests talking with a doctor or registered dietitian first. These thresholds are our own conservative flags, not official limits.
Calories to gain weight
To gain weight, eat more than your maintenance calories. The mild and regular gain targets add 250 and 500 calories a day. The macro calculator turns any calorie target into grams of protein, carbohydrate and fat.
How accurate are calorie calculators?
Any equation predicts the average for people with your measurements. In the Mifflin-St Jeor study, weight, height and age explained about 71% of the variation in measured resting energy, so individuals can differ noticeably from the prediction. Body composition matters too: in the same study, fat-free mass was the best single predictor of resting energy, so two people with the same height and weight but different amounts of muscle can burn different amounts. Activity multipliers add further uncertainty. To see what your measurements say about body composition, try the body fat calculator; for your resting calories alone, use the BMR calculator; and for a quick weight-for-height check, see the BMI calculator.
Frequently asked questions
How many calories should I eat a day?
It depends on your age, sex, size and activity, which is why a single number such as 2,000 is only a general reference. The Dietary Guidelines for Americans estimate that adult women need roughly 1,600 to 2,400 calories a day and adult men roughly 2,000 to 3,000, with sedentary people at the low end. An equation such as Mifflin-St Jeor personalizes that estimate, and your weight trend over a few weeks shows whether it fits you.
How many calories should I eat to lose weight?
A common approach is to eat about 500 calories a day less than your maintenance calories. For the example on this page that is 1,633 instead of 2,133 calories. The rule of thumb says that should lose about 1 lb a week, but real loss is usually slower and tapers over time. Very low targets are best followed only with guidance from a doctor or registered dietitian.
Is the 3,500-calorie rule accurate?
Only as a rough short-term guide. The rule assumes each 3,500 calories cut equals a pound lost, forever. Researchers comparing it with carefully controlled weight-loss studies found it overestimates actual loss. That is why the rates in this calculator are labeled as approximate and should not be read as a promise.
What is the difference between BMR and TDEE?
BMR (basal metabolic rate) is the energy your body uses at rest to keep you alive. TDEE (total daily energy expenditure) adds the calories burned by daily movement and exercise. This calculator estimates BMR with the Mifflin-St Jeor equation and multiplies it by an activity factor from 1.2 to 1.9 to get TDEE. For the example on this page, a BMR of 1,376 becomes a TDEE of 2,133.
Which activity level should I choose?
Choose the level that matches a typical week, not your best week. Sedentary (× 1.2) fits a desk job with little exercise; lightly active (× 1.375) fits light exercise one to three days a week; moderately active (× 1.55) fits three to five days. Most people overestimate their activity, so if you are unsure, pick the lower level and adjust after a few weeks of tracking your weight.
What is the lowest safe number of calories?
There is no single number that is safe for everyone. A federal clinical guide for treating obesity (NHLBI) generally uses 1,000 to 1,200 calories a day for most women and 1,200 to 1,600 for men, and says diets should not go below 800 calories a day. This calculator flags targets under 1,200 calories for women and 1,500 for men and suggests professional guidance.
Why is my weight not changing on my calculated calories?
Equations estimate an average person with your measurements, and real people differ. Calorie counts on labels and in apps are also approximate, and activity is easy to overestimate. Track your weight for three to four weeks; if it is stable at a given intake, that intake is your practical maintenance level, whatever the equation says.