🔥 Calorie Deficit: Calculator

Find your target daily calories to reach a healthy weight loss goal.

yrs
cm
kg
TARGET DAILY CALORIES
0 kcal
to reach your selected weekly loss goal
Maintenance (TDEE)
0 kcal
Daily Deficit
0 kcal
Est. Weekly Loss
0 kg
BMR
0 kcal
Mifflin-St Jeor equation used for BMR; 1 kg of body fat ≈ 7,700 kcal.

How the Calorie Deficit Calculator Works

To lose weight, you need to consistently eat fewer calories than your body burns — this gap is called a calorie deficit. This calculator first estimates your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, multiplies it by an activity factor to estimate your Total Daily Energy Expenditure (TDEE, your maintenance calories), and then subtracts your chosen daily deficit to give you a target daily calorie intake.

BMR (men) = 10W + 6.25H − 5A + 5
BMR (women) = 10W + 6.25H − 5A − 161
TDEE = BMR × Activity Multiplier
Target Calories = TDEE − Daily Deficit   (W=kg, H=cm, A=years)

Choosing a Safe, Sustainable Deficit

A deficit of about 500 kcal/day is a widely cited moderate target, generally corresponding to roughly 0.5 kg (about 1 lb) of fat loss per week, since one kilogram of body fat contains approximately 7,700 kcal of stored energy. Larger deficits can produce faster short-term results but are harder to sustain and more likely to lead to muscle loss, fatigue, or rebound weight gain.

Important Health Note

This calculator provides a general estimate based on standard formulas. It is not personalized medical or nutritional advice. If you have a medical condition, are pregnant, or are considering a significant or rapid weight change, talk to a doctor or registered dietitian first.

📎 Related Tools: Calorie Calculator TDEE Calculator BMR Calculator Macro Calculator

❓ Frequently Asked Questions

How big should my calorie deficit be to lose weight safely?
A moderate deficit of around 500 kcal/day (roughly 0.5 kg or 1 lb per week) is commonly recommended as a sustainable pace. Very large deficits can lead to muscle loss, fatigue, and are harder to maintain long-term.
Why does this calculator cap my target at 1,200 calories?
1,200 kcal/day is a commonly cited general floor below which it becomes difficult to meet basic nutritional needs for many adults. If your calculated target falls below this, consider a smaller deficit and consult a healthcare provider.
What's the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the energy your body needs at complete rest just to function. TDEE (Total Daily Energy Expenditure) adds your activity level on top of BMR, giving your actual estimated maintenance calories.
Does this calculator account for muscle loss during a deficit?
No — it estimates calories only. To help preserve muscle during a calorie deficit, many people combine a moderate deficit with adequate protein intake and resistance training, though this calculator doesn't model body composition changes.
Is 1 kg of fat really equal to 7,700 calories?
This is a widely used approximation based on the energy density of body fat tissue. It's a useful planning estimate, though real-world weight loss also involves water weight changes and isn't perfectly linear.

🏆 About This Tool — Accuracy & Trust

🔒 Data Privacy: All calculations run entirely within your browser using JavaScript. Nothing you enter here is ever transmitted to our servers, stored, sold, or shared.

📐 Accuracy Note: This tool uses standard, widely published formulas and guidelines. Results are estimates for informational purposes; for financial, medical, or engineering decisions, consult a licensed professional.

📅 Last Updated: September 2026.