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Calorie Deficit Calculator

Calculate your daily calorie needs and optimal deficit for healthy weight loss

Personal Information

Enter your age in years
Enter your height in centimetres
Enter your current weight in kilograms
Select the option that best describes your typical week
Slower weight loss is generally more sustainable

Understanding Calorie Deficit

What is a calorie deficit?

A calorie deficit occurs when you consume fewer calories than your body burns. This forces your body to use stored fat for energy, leading to weight loss.

Safe deficit guidelines

  • 250-500 cal deficit: 0.25-0.5 kg/week loss
  • 500-750 cal deficit: 0.5-0.75 kg/week loss
  • 750+ cal deficit: Consult healthcare professional

Key formulas used

BMR: Your body's energy needs at rest
TDEE: BMR × Activity Factor
Deficit: TDEE - Target Calories

How It Works

BMR Calculation

We use the Mifflin-St Jeor equation, considered the most accurate for most people:

  • Men: (10 × weight kg) + (6.25 × height cm) - (5 × age) + 5
  • Women: (10 × weight kg) + (6.25 × height cm) - (5 × age) - 161

Activity Factors

  • Sedentary: 1.2
  • Lightly Active: 1.375
  • Moderately Active: 1.55
  • Very Active: 1.725
  • Extra Active: 1.9

Important Considerations

  • These are estimates - individual metabolism varies
  • Start conservatively and adjust based on results
  • Very low calorie diets can slow metabolism
  • Include strength training to preserve muscle mass
  • Consider cycling calories or having refeed days

When to Seek Help

  • If you have underlying health conditions
  • For deficits larger than 1000 calories/day
  • If you experience fatigue, mood changes, or hunger
  • For personalised nutrition planning