How many calories do I need a day? Calculator and formula
Knowing how many calories you need is the first step to losing weight, maintaining or building muscle. Here is a calculator with the same formula the app uses, how it works step by step and how to adjust the result to your goal.
Key takeaways
- Daily needs = basal metabolic rate × activity factor.
- Mifflin-St Jeor is the most widely used formula to estimate it.
- To lose weight, eat about 15% less.
- It is an estimate: adjust it based on how your weight changes.
Daily calorie calculator
Enter your details and choose your goal. We use the same formula as the Pondera Health app to work out your calorie target and your macros.
1,953calories a day
- Basal metabolic rate1420 kcal
- Maintenance1953 kcal
- Protein122 g
- Carbs220 g
- Fat65 g
How it works: two steps
1. Your basal metabolic rate
This is what your body burns at rest to breathe, keep warm and run your organs. The most widely used formula to estimate it is Mifflin-St Jeor:
- Women: 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
- Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Example: a 30-year-old woman who weighs 70 kg and is 165 cm tall has a basal metabolic rate of about 1,420 kcal.
2. Your activity level
Next, add what you burn by moving. To do that, multiply by an activity factor:
| Level | What your week looks like | Factor |
|---|---|---|
| Sedentary | Desk job and almost no exercise | × 1.2 |
| Light | Light exercise 1 to 3 days a week | × 1.375 |
| Moderate | Exercise 3 to 5 days a week | × 1.55 |
| High | Hard exercise 6 to 7 days a week | × 1.725 |
| Very high | Physical job or training twice a day | × 1.9 |
In the example, with light activity: 1,420 × 1.375 ≈ 1,953 kcal a day. That is her maintenance calories: what she needs to neither gain nor lose weight.
Calories for your goal
- Maintain your weight: eat your maintenance calories.
- Lose weight: eat about 15% less. In the example, about 1,660 kcal. We explain it in our calorie deficit guide.
- Build muscle: eat about 10% more and lift weights.
An estimate, not an exact number
Every formula gives an average. Your real needs may be a little higher or lower. So use the number as a starting point and adjust it based on what happens:
- Log what you eat and your weight for 2 or 3 weeks.
- If your weight doesn’t move as expected, adjust your target by 100 to 200 kcal.
- Recalculate when your weight or activity changes a lot.
Once you have your number, the next step is to split it well. Read our guide on how to calculate your macros.
Frequently asked questions
How many calories does a woman need a day?
It depends on her weight, height, age and activity. As a reference, a 30-year-old woman who weighs 70 kg, is 165 cm tall and lightly active needs about 1,950 kcal to maintain her weight.
What is basal metabolic rate?
It is the energy your body burns at rest to keep its basic functions going. It is usually most of what you burn in a day.
What is the most accurate formula to calculate calories?
For healthy adults, Mifflin-St Jeor is one of the most widely used and accurate. It is still an estimate: adjust it with your real weight.
How often should I recalculate my calories?
When your weight changes by about 3 to 5 kg, or your activity changes a lot, for example when you start or stop training.
Sources
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. doi.org/10.1093/ajcn/51.2.241
- FAO/WHO/UNU. Human energy requirements. Food and Nutrition Technical Report Series 1. Rome, 2004. www.fao.org/4/y5686e/y5686e00.htm
- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press, 2005. doi.org/10.17226/10490
We write nutrition guides with the same calculations and sources the app uses, cited at the end of each article.
This content is for information only and does not replace advice from a doctor or dietitian. If you have a health condition, are pregnant or take medication, check with a professional before changing how you eat.
