Calorie Deficit Calculator
A calorie deficit means eating fewer calories than your body burns. Enter your details, current weight and goal weight, and this calculator shows how many calories to eat each day to lose weight safely, and roughly when you'll reach your goal.
A deficit of 300 to 500 kcal/day is sustainable for most people and preserves muscle better than large cuts. Losing more than 1% of your body weight a week raises the risk of muscle loss, fatigue and rebound weight gain, so this calculator caps the rate.
Target Daily Intake
Deficit: -530 kcal (27%)Eat 1420 calories a day to lose approximately 0.48 kg per week. Projected goal date: 2027-01-22.
Maintenance TDEE
1950 kcal
Zero loss intake
Daily Deficit
-530 kcal
27% reduction
Estimated Duration
17 weeks
~116 days
Deficit Scenarios Compared
| Deficit Level | Daily Target | Weekly Loss | Timeline |
|---|---|---|---|
| Mild (-250 kcal/day) | 1700 kcal | 0.23 kg/wk | 35 wks |
| Moderate (-500 kcal/day) | 1450 kcal | 0.45 kg/wk | 18 wks |
| Faster (-750 kcal/day) | 1200 kcal | 0.68 kg/wk | 12 wks |
Loss usually slows as body weight drops; recalculate your deficit every 3 to 5 kg lost.
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Clinical Equations
WHO, CDC, ACSM & Mifflin-St Jeor
Suggest a Feature or Improvement for Calorie Deficit Calculator
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How to use Calorie Deficit Calculator
- 1Enter your age, sex, height, current weight, and activity level.
- 2Enter your target goal weight.
- 3Choose whether you want to target a specific weekly loss rate or a target completion date.
- 4Receive your daily calorie ceiling, safe deficit boundary, and projected milestone timeline.
What is an effective calorie deficit?
One kilogram of human adipose body fat stores roughly 7,700 kcal of energy (3,500 kcal per pound). Creating an energy deficit of 500 kcal each day results in approximately 0.45 to 0.5 kg of fat loss per week.
Excessive deficits slow thyroid output, increase cortisol, cause lean muscle wasting, and trigger ravenous hunger. Moderation is key to permanent fat loss.
Safety floors
This tool automatically clamps your caloric recommendation at your Basal Metabolic Rate and clinical thresholds (1,200 kcal for women, 1,500 kcal for men). If a user enters an extreme deficit, a warning message prompts moderation.
Frequently Asked Questions
How much weight will I lose with a 500-calorie deficit?
About 0.45 kg (1 lb) per week initially. Because metabolic rate adjusts as body mass drops, weight loss naturally tapers over time.
Can a calorie deficit be too big?
Yes. Deficits exceeding 1,000 kcal/day or 1% of body weight per week accelerate lean muscle catabolism and can lead to nutrient deficiencies and metabolic adaptation.
Why am I not losing weight in a deficit?
Common causes include unmeasured cooking oils, fluid retention from high sodium or new workouts, or an overestimated exercise multiplier. Track consistently for 2–3 weeks before adjusting.
Should I eat back exercise calories?
Your chosen activity multiplier already accounts for workout energy. Adding burned calories back onto your meal plan often leads to inadvertent overeating.
Related Calculators
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TDEE Calculator
Estimate your Total Daily Energy Expenditure and discover your true maintenance calories.
Weight Loss Timeline Calculator
Project your realistic week-by-week weight loss timeline with adaptive metabolic rate tracking.
Macro Calculator
Calculate your daily macronutrients (protein, carbs, and fat) for weight loss or muscle building.
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Calculate your daily protein requirements based on body weight, fitness goals, and training intensity.
Scientific Sources & Evidence
- World Health Organization (WHO) — Body Mass Index Classification
- CDC Growth Charts — BMI-for-age LMS Percentiles
- Mifflin et al. (1990) — Basal Metabolic Rate Predictive Equations
- NICE Guideline NG246 — Identification and Management of Overweight and Obesity
- American College of Sports Medicine (ACSM) — Exercise Testing & Prescription
- European Food Safety Authority (EFSA) — Dietary Reference Values for Water