“How many calories should I eat?” sounds like it should have one answer. It doesn’t, because your number depends on your body and your day. But you can get a good estimate in a few minutes, and that estimate is all you need to start. Here’s how it works.
The short answer
According to the US Dietary Guidelines, most adult women need roughly 1,600–2,400 calories a day and most adult men roughly 2,200–3,000 to maintain their weight. The low end is for people who sit most of the day, the high end for very active people. That range is wide, so the rest of this article shows how to narrow it down to your own number.
Step 1: Your BMR, the energy you burn at rest
Your basal metabolic rate (BMR) is what your body burns just to keep you alive: breathing, circulation, keeping warm. For most people it’s the biggest part of the daily total. The most widely used way to estimate it is the Mifflin-St Jeor equation, which a systematic review found to be the most reliable of the common formulas, landing within 10% of measured values for more people than the alternatives.
- Women: 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
- Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Step 2: Add your activity, and you get your TDEE
Your total daily energy expenditure (TDEE) is your BMR plus everything you do on top of it: walking, working, training, even fidgeting. To estimate it, multiply your BMR by an activity factor:
- Mostly sitting, little exercise: × 1.2
- Light exercise 1–3 days a week: × 1.375
- Moderate exercise 3–5 days a week: × 1.55
- Hard exercise 6–7 days a week: × 1.725
Most people overestimate how active they are. If you’re unsure between two levels, pick the lower one.
Two worked examples
| BMR | Mostly sitting (× 1.2) | Moderately active (× 1.55) | |
|---|---|---|---|
| Woman, 35, 165 cm, 65 kg | about 1,345 | about 1,610 | about 2,085 |
| Man, 35, 180 cm, 80 kg | about 1,755 | about 2,105 | about 2,720 |
Notice how much activity changes the answer: the same woman needs almost 500 calories more on an active routine than on a mostly seated one.
What to do with your number
- To maintain your weight: eat around your TDEE.
- To lose weight: eat somewhat below it. A moderate gap is easier to keep up than a big one, and you’re less likely to feel drained.
- To gain weight or build muscle: eat somewhat above it, ideally with enough protein. Our guide to how much protein you really need covers that part.
One honest caveat: weight change isn’t perfectly linear. Research from the US National Institutes of Health shows that as you eat less, your body adapts and weight loss gradually slows, which is why the old “cut 3,500 calories, lose a pound” rule overpromises. Treat your number as a starting point, then adjust based on what actually happens over a few weeks.
It’s an estimate, not a verdict
Equations predict averages, and your body isn’t an average. Two people with the same age, height and weight can differ by a few hundred calories. That’s why the most useful thing you can do is compare your estimate with real life: track what you eat for two or three weeks, watch your weight trend, and nudge your target up or down.
If you’re pregnant or breastfeeding, managing a medical condition, or have a history of disordered eating, talk to your doctor or a registered dietitian before setting a calorie target.
Let the app do the math
When you set up MyCalorie AI, it estimates your daily target from your age, height, weight and goal using the same Mifflin-St Jeor equation, and you can fine-tune your activity level later in your profile. Then you just snap a photo of your meal or describe it in a sentence, and you see how each day compares with your target.
This article is general information, not medical advice. Individual needs vary.
Sources
- US Department of Agriculture and US Department of Health and Human Services. Dietary Guidelines for Americans, 2020–2025 (estimated calorie needs, Appendix 2).
- Mifflin M.D. et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990.
- Frankenfield D. et al. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc, 2005.
- Hall K.D. et al. Quantification of the effect of energy imbalance on bodyweight. Lancet, 2011 (basis of the NIH Body Weight Planner).