How this calculator works
The calculator estimates your basal metabolic rate (BMR) — the energy your body burns at complete rest — with the Mifflin-St Jeor equation, then multiplies it by an activity factor to get your total daily energy expenditure (TDEE). Your goal then shifts the target: a deficit below TDEE to lose weight, a surplus above it to gain.
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Mifflin-St Jeor is the formula most evidence-based apps and dietitians default to — comparative studies have found it more accurate than the older Harris-Benedict equation for modern populations. It's also exactly what the CalTracker app uses when it sets your daily calorie goal during onboarding.
Activity multipliers
| Level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, little or no exercise | 1.2 |
| Lightly active | Exercise 1–3 days/week | 1.375 |
| Moderately active | Exercise 3–5 days/week | 1.55 |
| Very active | Exercise 6–7 days/week | 1.725 |
| Extremely active | Physical job plus hard training | 1.9 |
Most people overestimate their activity level. If you sit most of the day and train three times a week, "lightly active" or "moderately active" is usually closer to the truth than "very active".
What to do with your number
- Pick the gentle or steady pace. A ~500 kcal/day deficit (≈0.5 kg per week) is the classic sustainable starting point. Aggressive deficits work on paper and fail in kitchens.
- Track against it for 2–3 weeks. Every formula is an estimate; your real TDEE shows up in the trend line of your weight. Adjust by 100–200 kcal if the scale disagrees with the math.
- Watch the weekly average, not single days. One high day changes nothing if the week averages out.
That second step — logging what you actually eat — is the hard part, and it's the problem CalTracker exists to make easy: snap a photo and the AI estimates calories and macros, or scan a barcode, or search the food database. It works fully offline once you're signed in, and the free tier includes all core tracking.
FAQ
How accurate is this calorie calculator?
It uses the most validated general-purpose formula available, but every formula is an estimate — individual metabolisms vary by roughly ±10%. Treat the number as a starting point and calibrate against two to three weeks of real tracking data.
What is TDEE exactly?
Total Daily Energy Expenditure: everything you burn in a day — resting metabolism, digestion, daily movement, and exercise. Eat at TDEE and your weight stays put; that's why it's also called "maintenance calories".
How big should my calorie deficit be?
About 500 kcal/day is the standard sustainable recommendation (~0.5 kg or 1 lb per week). Going below ~1,200 kcal (women) or ~1,500 kcal (men) for extended periods isn't advisable without medical supervision — the calculator will warn you if your target lands there.
Why does this differ from other calculators?
Different sites use different formulas (Harris-Benedict, Katch-McArdle) and rounder activity multipliers. Differences of 50–150 kcal between calculators are normal and matter less than consistent tracking.
Does CalTracker use the same formula?
Yes — the app calculates your calorie goal with Mifflin-St Jeor from the same inputs during onboarding, then tracks your actual intake and weight against it, including a probability estimate of hitting your goal by your target date.
This calculator provides general estimates for healthy adults and is not medical advice. Calorie needs vary with individual health conditions. Consult a doctor or registered dietitian before starting a diet, especially if you are pregnant, under 18, have a medical condition, or have a history of disordered eating.
