A calorie target you can inspect, not just accept.
Estimate maintenance calories, a starting goal, protein, carbs, fat, and water. See the assumptions before deciding what to do next.
Get your starting estimate
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A useful starting point, with the assumptions shown.
You will get estimated resting energy, maintenance calories, a calorie target, macros, and water.
Four steps, with no hidden precision.
- 1
Estimate resting energy
Mifflin–St Jeor estimates the energy an adult body uses at rest from sex, age, height, and weight.
- 2
Apply an activity range
Your activity choice turns resting energy into an estimated maintenance range. It is an assumption, not a measurement.
- 3
Add the goal
A modest deficit, maintenance target, or surplus creates a starting calorie plan with a safety floor.
- 4
Set macro planning targets
Protein and fat are set from body weight and goal; carbohydrates use the remaining planned energy.
Useful for planning. Not a diagnosis.
- Population equations can be meaningfully wrong for an individual.
- Activity labels are broad and people often move differently from week to week.
- Medication, health conditions, pregnancy, breastfeeding, and eating-disorder history need individualized guidance.
- Short-term scale changes include water, glycogen, and digestion—not only tissue change.
Common questions about calories and macros
How many calories should I eat a day?
It depends on your sex, age, height, weight, and how active you are, so there is no single right number. The calculator estimates resting energy with Mifflin–St Jeor, multiplies it by an activity factor to get maintenance calories, then adjusts for your goal. Treat the result as a starting point and adjust by 100–200 kcal a day if your weight trend over two to three weeks does not match your goal.
What are maintenance calories?
Maintenance calories are the energy that keeps your body weight roughly stable, also called total daily energy expenditure (TDEE): resting energy plus what you burn through daily movement, exercise, and digesting food. Formulas only estimate it, and for an individual the real number can be 10% or more away.
How do I calculate my macros?
Start from a calorie target, set protein and fat, then give the remaining calories to carbohydrates. This calculator sets protein and fat from your body weight and goal. Protein and carbohydrates provide about 4 kcal per gram and fat about 9 kcal per gram, which is how grams turn into calories.
How many carbs should I eat per day?
Many dietary guidelines put carbohydrates at roughly 45–60% of daily calories, but the right amount depends on your total calories, activity, and preferences. Here carbs are what remains after protein and fat, so they rise with activity and fall in a deficit. If you have diabetes or another medical condition, set carbohydrate targets with your clinician.
How big should a calorie deficit be?
A moderate deficit is usually easier to sustain than an aggressive one. The calculator plans weight loss as a weekly pace of 0.25–1% of body weight, converts it at about 7,700 kcal per kilogram, and never goes below a floor of 1,200 kcal for women, 1,500 kcal for men, or 110% of estimated resting energy, whichever is higher.
Sources and next reading
The resting-energy equation comes from the original Mifflin–St Jeor study. A systematic review found it among the more reliable common equations while still documenting individual error.