Calorie & BMR Calculator
Find your daily calorie needs based on size, age, activity and goal.
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BMI = 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 ≈ 22.9 — Normal weight
📘 What is the Calorie & BMR Calculator?
Every weight-management goal — losing fat, gaining muscle, or maintaining your current weight — ultimately comes down to the relationship between calories consumed and calories burned. This calculator estimates your Basal Metabolic Rate (BMR, the energy your body uses at complete rest) and your Total Daily Energy Expenditure (TDEE, your BMR plus activity), then shows the calorie target for your specific goal.
⚙️ How Calories / BMR is calculated
BMR — your body's baseline energy use
BMR represents the calories your body burns just to keep you alive — breathing, circulating blood, maintaining body temperature, cell repair — with zero physical activity. This calculator uses the Mifflin-St Jeor equation, widely considered one of the more accurate formulas for estimating BMR from weight, height, age, and sex.
TDEE — adding your activity level
TDEE = BMR × an activity multiplier (typically ranging from about 1.2 for sedentary lifestyles to 1.9+ for very active individuals with physical jobs or intense training). TDEE represents your actual daily calorie burn — the number that matters for weight management, since it accounts for everything BMR doesn't.
Why a 500 kcal deficit ≈ 0.5 kg/week
One kilogram of body fat represents roughly 7,700 kcal of stored energy. A consistent daily deficit of 500 kcal therefore creates a weekly deficit of approximately 3,500 kcal — close to 0.5 kg of fat loss per week. This is the basis for the commonly cited "500 kcal deficit for steady weight loss" guideline, though individual results vary due to water retention, metabolic adaptation, and measurement noise.
Why this number needs to be recalculated periodically
As you lose or gain weight, your BMR changes — a lighter body requires less energy at rest. This calculator's recommendation to recalculate every 5 kg of weight change exists because a calorie target set for your starting weight will gradually become inaccurate (too generous for weight loss, or insufficient for weight gain) as your weight changes.
Mifflin-St Jeor BMR (metric)
Men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5 Women: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161
TDEE = BMR × activity multiplier (1.2–1.9+)
🧮 Worked examples
Example 1 — Sedentary office worker
30-year-old woman, 65 kg, 165 cm, sedentary lifestyle (activity multiplier 1.2), goal: maintain weight.
→ BMR ≈ 1,365 kcal · TDEE ≈ 1,640 kcal · Maintenance target ≈ 1,640 kcal/day
Example 2 — Active man aiming for fat loss
35-year-old man, 85 kg, 178 cm, moderately active (multiplier 1.55), goal: lose 0.5 kg/week.
→ BMR ≈ 1,790 kcal · TDEE ≈ 2,775 kcal · Target with 500 kcal deficit ≈ 2,275 kcal/day
Example 3 — Recalculating after 5 kg loss
Same man as Example 2, after losing 5 kg (now 80 kg), same activity level.
→ New BMR ≈ 1,725 kcal · New TDEE ≈ 2,675 kcal — about 100 kcal/day lower than before, illustrating why targets need periodic recalculation
💡 Original insights & how to use this calculator
Choosing an honest activity multiplier
The most common error in TDEE estimates is overestimating activity level — "moderately active" assumes structured exercise most days, not just an active job. If your weight tracking over 2-3 weeks doesn't match the predicted trend at your calculated target, your actual activity level (and therefore TDEE) is likely lower than selected — try the next level down.
Why aggressive deficits often backfire
A deficit much larger than 500-750 kcal/day (e.g., aiming to lose 1+ kg/week through diet alone for non-medical reasons) increases the risk of significant muscle loss alongside fat loss, and tends to be harder to sustain. This calculator deliberately frames its loss-rate suggestions around the 0.5 kg/week range as a sustainable default.
Using TDEE for muscle gain, not just loss
The same TDEE number works in reverse for muscle gain: a modest surplus of 200-300 kcal/day above TDEE, combined with resistance training, supports gradual muscle gain while limiting fat gain. Enter your TDEE here, then add this surplus manually for a gain-focused target.
Calories are a tool, not a moral measurement
This calculator provides a starting estimate, not a rigid prescription — actual energy needs vary by 10-15% even between people with identical stats due to individual metabolic differences. Use the number as a starting point, track real-world results for 2-3 weeks, and adjust based on what you observe rather than treating the initial estimate as exact.
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💡 Expert tips
Recalculate every 5 kg of weight change.
500 kcal daily deficit ≈ 0.5 kg fat loss per week.
⚖️ Health & Wealth — pair this with
Budget Planner
Tracking calories and tracking spending use the same skill — noticing where the numbers actually go versus where you assume they go.
Compound Interest
A small daily calorie deficit compounds into significant fat loss over months, the same way small daily savings compound into significant wealth over years.
📖 Learn more on WellFiLab
Visit ↗❓ Common questions
What is BMR?
Basal Metabolic Rate — calories burned at complete rest.
What is TDEE?
Total Daily Energy Expenditure — your actual daily calorie burn.
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