Daily Calorie Needs Calculator
Estimate total daily calorie needs (TDEE) by combining the revised Harris-Benedict BMR formula with an activity multiplier. The number to eat at for maintenance, subtract from for fat loss, or add to for muscle gain.
Last updated: May 2026
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About this calculator
TDEE is total daily energy expenditure — the calories your body burns over 24 hours from all sources combined. This calculator first computes basal metabolic rate (BMR) using the male revised Harris-Benedict equation: BMR = 88.362 + (13.397 × weight kg) + (4.799 × height cm) − (5.677 × age). It then multiplies by an activity factor: 1.2 (sedentary — desk job, no exercise), 1.375 (light — light exercise 1–3 days/week), 1.55 (moderate — exercise 3–5 days/week), 1.725 (high — hard exercise 6–7 days/week). The result is approximate calories burned per day. Variables: weight in kg; height in cm; age in years; activity multiplier. Notable limitation of this specific calculator: it uses the male Harris-Benedict formula regardless of sex. For females, BMR is typically 100–250 kcal lower for the same weight, height, and age, so this calculator will overstate TDEE for women by roughly that amount. For accurate sex-specific BMR, use a BMR calculator with a gender input and then multiply by activity. Edge cases: BMR formulas were derived from healthy adults aged 18–65 and lose accuracy at extremes — very lean athletes underestimate, severely obese individuals overestimate, and elderly adults often have lower BMR than predicted due to muscle loss. Activity multipliers chronically overstate real expenditure by 10–30% in studies using doubly-labelled water; treat the output as a starting hypothesis to refine against actual weight change over 2–3 weeks. For most people, a 500-kcal daily deficit produces roughly 0.5 kg/week of fat loss; a 200–300 kcal surplus combined with strength training produces slow lean gain.
How to use
Example 1 — Active adult. You weigh 75 kg, are 175 cm tall, 28 years old, and exercise moderately (4 days/week). Enter Weight = 75, Height = 175, Age = 28, Activity = Moderate (1.55). BMR = 88.362 + (13.397 × 75) + (4.799 × 175) − (5.677 × 28) = 88.362 + 1004.78 + 839.83 − 158.96 ≈ 1774 kcal. TDEE = 1774 × 1.55 ≈ 2750 kcal/day. ✓ Eat at 2750 for maintenance; ~2250 for fat loss (~0.5 kg/week); ~3000 for slow muscle gain. Example 2 — Sedentary office worker. Same body dimensions but a desk job and no exercise. Enter 75, 175, 28, Sedentary (1.2). BMR ≈ 1774 (same as Example 1). TDEE = 1774 × 1.2 ≈ 2129 kcal/day. ✓ Notice the impact of activity: same BMR, 600 kcal/day difference in maintenance calories from just the activity multiplier change. This is why active people can "eat more" — not because of a faster metabolism, but because they're burning calories through movement throughout the day.
Frequently asked questions
Why does this calculator use the male formula even for women?
This particular implementation simplifies by using the male revised Harris-Benedict equation regardless of sex. The female equation is BMR = 447.593 + (9.247 × weight kg) + (3.098 × height cm) − (4.330 × age), and produces values typically 100–250 kcal lower than the male equation for the same body dimensions. For women using this calculator, the TDEE output is likely overstated by roughly that amount — a 28-year-old, 65 kg, 168 cm woman would get ~1700 kcal BMR from the male formula but ~1430 from the proper female formula. The practical implication: women using this tool should probably subtract 150–250 kcal from the output, or use a calculator that asks for biological sex. For weight management purposes, the difference matters — eating at the over-estimated maintenance level may stall fat loss; under-eating creates risks of nutritional inadequacy. Treat the number as approximate either way and calibrate against actual weight change.
How accurate are activity multipliers?
They're population averages and frequently overestimate real expenditure. Studies using doubly-labelled water (the gold standard for measuring true energy expenditure) consistently show that self-reported activity levels overstate true expenditure by 10–30%. Two mechanisms: people overestimate how much they exercise, and NEAT (non-exercise activity thermogenesis — fidgeting, posture, spontaneous movement) often drops in compensation when structured exercise increases. An office worker who goes to the gym 3 times a week may think they're "moderately active" (1.55) but may actually be closer to "lightly active" (1.375). A reliable approach is to start with the calculated TDEE, eat at that level for 2–3 weeks while tracking weight, then adjust by ±100–200 kcal/day based on whether weight is stable, rising, or falling. Personal calibration always beats formula prediction.
How do I use TDEE to plan fat loss or muscle gain?
For fat loss, eat below TDEE — a 500 kcal/day deficit gives ~0.5 kg/week (since 3500 kcal ≈ 0.5 kg of fat), and 1000 kcal/day gives ~1 kg/week. Deficits over 1000 kcal/day are hard to sustain and often cause muscle loss; for the last 5 kg of a cut, smaller deficits (250–500 kcal) preserve muscle better. For muscle gain, eat above TDEE by 200–500 kcal combined with progressive strength training; gaining faster than ~0.25 kg/week of true muscle is generally impossible, and surplus beyond that becomes fat. Recompute TDEE every 5–10 kg of weight change because BMR shifts with body mass. Track weekly average weight rather than daily readings to filter out water and digestive noise. Pair calorie targets with adequate protein (1.6–2.2 g/kg for active people) and strength training to preserve or build lean tissue.
What are the most common mistakes using calorie calculators?
The first is selecting too high an activity multiplier — most people who say they're "very active" are really lightly to moderately active by objective measurement, so they overeat thinking they're at maintenance. The second is treating the output as exact when individual variation is 10–15% even before considering tracking error. The third is forgetting that BMR drops as you lose weight; the maintenance number from 10 kg ago is no longer valid. The fourth is ignoring food-intake tracking error — under-reporting of food intake is universal in nutrition studies (the "memory deficit"), typically 20–40% in self-reported logs. The fifth is swinging between extreme deficits and surpluses; sustainable modest deficits of 300–500 kcal/day work much better than 1000+ kcal/day crash dieting. Finally, people often forget that water, glycogen, and gut contents fluctuate body weight 1–3 kg daily, so trust weekly averages, not daily readings.
When should I not use this calculator?
Skip it if you're female and want accurate results — use a calculator with a gender input that applies the female Harris-Benedict or Mifflin-St Jeor equation. Don't use it under 18 — children and adolescents have different metabolic rates and need pediatric equations plus growth-related energy. Skip during pregnancy and lactation, which add roughly 300 and 500 kcal/day to maintenance respectively, and require dedicated calculators. It's unreliable for people with significant medical conditions affecting metabolism (untreated thyroid disorders, recent major surgery, severe burns, cancer cachexia, eating-disorder recovery); those situations need clinical indirect calorimetry. It's also a poor fit at body composition extremes: elite bodybuilders with very high lean mass underestimate, severely obese individuals (BMI > 40) tend to overestimate. For any of those groups, a registered dietitian or sports medicine physician should interpret needs in context.