Calorie Calculator: Personalized Daily Intake & Weight Management Tool

How to use the tool

1. Gender – pick female or male. Sample: female or male aged 42.
2. Activity level – reflect your week. Examples: Sedentary: office work, no exercise or Extra Active: bike courier.
3. Formula – choose: Mifflin St Jeor, Revised Harris-Benedict, or Katch-McArdle (needs body-fat %).
4. Weight (kg) – enter mass, e.g., 90 kg or 54.5 kg.
5. Height (cm) – add stature, e.g., 175 cm or 158 cm.
6. Age (15-80) – input 23 years or 67 years.
7. Body-fat % – only for Katch-McArdle: 22 % or 14 %.
8. Calculate – read calories for losing, maintaining, or gaining weight.

Core formulas

• Mifflin St Jeor
  $$\text{BMR}_{m}=10W+6.25H-5A+5$$ $$\text{BMR}_{f}=10W+6.25H-5A-161$$ (Mifflin et al., 1990)
• Revised Harris-Benedict
  $$\text{BMR}_{m}=13.397W+4.799H-5.677A+88.362$$ $$\text{BMR}_{f}=9.247W+3.098H-4.330A+447.593$$ (Roza & Shizgal, 1984)
• Katch-McArdle
  $$\text{BMR}=370+21.6\,\times\,LBM$$ $$LBM=W\,(1-\frac{BF}{100})$$ (Katch & McArdle, 1996)

Convert BMR to total daily energy expenditure (TDEE) with the multiplier: Sedentary 1.2 … Extra Active 1.9 (FAO/WHO/UNU, 2001).

Example calculations

Example A – Revised Harris-Benedict, sedentary male

• W = 90 kg, H = 175 cm, A = 40 y
• BMR = 13.397×90 + 4.799×175 − 5.677×40 + 88.362 = 1906.8 cal
• TDEE = 1906.8 × 1.2 = 2288 cal

Example B – Mifflin St Jeor, active female

• W = 55 kg, H = 160 cm, A = 23 y
• BMR = 10×55 + 6.25×160 − 5×23 − 161 = 1274 cal
• TDEE = 1274 × 1.55 ≈ 1975 cal

Example C – Katch-McArdle, moderate male

• W = 78 kg, BF = 20 %, A = 35 y
• LBM = 78 × 0.8 = 62.4 kg
• BMR = 370 + 21.6 × 62.4 = 1717.8 cal
• TDEE = 1717.8 × 1.465 ≈ 2516 cal

Quick-Facts

• BMR accounts for 60-75 % of total energy use (Heymsfield et al., 2014).
• Deficit of 7700 cal equals ≈1 kg fat loss (Hall et al., 2012).
• Healthy loss pace: 0.25-1 kg/week (CDC, 2022).
• PAL multipliers span 1.2 to 1.9 (FAO/WHO/UNU, 2001).
• Body-fat under 25 % suits Katch-McArdle (NSCA Guide, 2017).

FAQ

What does the calculator provide?

Your maintenance calories and targets for ±0.25, 0.5, 1 kg per week using validated metabolic equations (Mifflin et al., 1990).

Which formula should you choose?

Mifflin suits most adults; Revised Harris-Benedict helps heavier bodies; Katch-McArdle excels when you know body-fat percentage (NSCA Guide, 2017).

How accurate are activity multipliers?

They stem from FAO/WHO/UNU standards and capture lifestyle variance within ±15 % error (FAO/WHO/UNU, 2001).

What calorie deficit promotes fat loss?

Create a 500 cal daily gap to shed about 0.45 kg weekly (NIH, 2020).

Why include body-fat percentage?

It lets Katch-McArdle tailor energy needs to lean mass, boosting precision for athletes (Katch & McArdle, 1996).

Does age affect calorie demand?

BMR drops roughly 1-2 % per decade after 20 years (Heymsfield et al., 2014).

How often should you recalculate?

Update every 4-6 weeks or after ±2 kg body change to stay accurate (ACSM, 2018).

Can you gain muscle while losing fat?

You can by combining mild calorie deficit with 1.6-2.2 g protein/kg and resistance training (Phillips, 2014).