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Weight Loss Calculator

Calculate how long it will take to reach your target weight with a calorie deficit.

Complete Guide

Overview

Sustainable weight loss requires a consistent caloric deficit. 1 kg of body fat contains approximately 7,700 kcal. A deficit of 500 kcal/day leads to roughly 0.45 kg of fat loss per week. This calculator shows how long it will realistically take to reach your target.

⚠️Consult a doctor or dietitian before starting a significant caloric deficit.

How to Use

Enter your current weight.

Enter your target weight.

Enter your planned daily calorie deficit (500 kcal/day is a safe, sustainable amount).

Click Calculate.

Formula & Calculation

kg to Lose ÷ (Deficit × 7 ÷ 7700) = Weeks
1 kg fat ≈ 7700 kcal

Example

15 kg loss, 500 kcal/day deficit → 15÷(500×7÷7700) = 15÷0.454 ≈ **33 weeks**

Benefits of Using This Calculator

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Realistic Timeline

Set achievable expectations for your journey.

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Goal-Focused

Keeps you motivated with a clear end date.

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Safe Planning

Encourages sustainable, healthy deficits.

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Track Progress

Adjust deficit based on real-world results.

Pro Tips

A deficit of 500–750 kcal/day is generally safe and sustainable.
Weight loss is non-linear — expect plateaus.
Include strength training to preserve muscle during weight loss.
Reassess every 4 weeks as your TDEE changes with weight loss.

In-Depth Guide

Weight Loss Calculator: How Long Will It Actually Take?

Setting a weight loss goal is easy. Knowing how long it will realistically take is harder. This calculator removes the uncertainty — give it your current weight, target, and planned calorie deficit, and it gives you an honest timeline backed by science.

The Science Behind It

One kilogram of body fat stores approximately 7,700 kilocalories of energy. To lose that kilogram, you need a 7,700 kcal deficit over time. At 500 kcal/day, that takes about 15 days per kilogram. Weight loss is not perfectly linear — it slows as your TDEE decreases — but as a planning tool, this formula is accurate and reliable.

The Formula

kg per week = (Daily Deficit × 7) ÷ 7700
Weeks to goal = Weight to Lose ÷ kg per week

Worked Example

Current: 95 kg. Target: 80 kg. Deficit: 500 kcal/day.

kg/week = (500 × 7) ÷ 7700 = 0.455 kg
Weeks = 15 ÷ 0.455 = 33 weeks (~8 months)

See your personalised timeline with our free Weight Loss Calculator.

Deficit Size vs Rate

Daily Deficit	Weekly Loss	Sustainability
250 kcal/day	~0.22 kg	Very sustainable
500 kcal/day	~0.45 kg	Recommended for most
750 kcal/day	~0.68 kg	Manageable, requires discipline
1000+ kcal/day	0.9+ kg	Very hard to sustain long-term

Why Planning Your Timeline Matters

Realistic expectations prevent quitting. People expecting fast results who hit plateaus often abandon their program entirely.
Avoids extreme restriction. Chasing rapid loss leads to muscle loss, nutrient deficiency, and rebound weight gain.
Shows the power of consistency. 500 kcal/day deficit × 365 days = roughly 24 kg of fat loss per year.

Practical Tips

Keep protein high. 1.6–2.2g per kg prevents muscle loss during a deficit.

Strength train throughout your cut. Resistance training signals the body to preserve muscle even while losing fat.

Track weekly averages. Daily weight fluctuates 1–2 kg from water. A 7-day average reveals the real trend.

Final Thoughts

Weight loss is consistent arithmetic over time. Know your deficit, maintain it, and the math takes care of the rest.

See exactly how long your journey will take with our free Weight Loss Calculator.

Consult a doctor or dietitian before starting a significant calorie deficit, especially with underlying health conditions.