How big should my calorie deficit be?

250-500 calories for sustainable loss (0.25-0.5 kg/week). 500-750 for faster loss. Never go below your BMR. Larger deficits risk muscle loss, fatigue, and metabolic slowdown.

How many calories should I eat to lose weight?

Calculate your TDEE, then subtract 500. For most adults: women 1,200-1,500 cal, men 1,500-1,800 cal for active weight loss. Our calculator gives your personalized number.

How long will it take to lose 10 kg?

At 0.5 kg/week (500-cal deficit): 20 weeks (5 months). At 0.75 kg/week (750-cal deficit): 13 weeks (3 months). Slower is more sustainable and preserves muscle.

Will a 1000-calorie deficit work?

It will lose weight fast (1 kg/week) but risks muscle loss, fatigue, nutrient deficiency, and metabolic adaptation. Only sustainable short-term. 500-750 is safer for most people.

Should I eat less or exercise more?

Both. Diet creates the deficit, exercise preserves muscle and boosts TDEE. A 300-cal diet reduction plus 200-cal exercise burn = 500 total deficit with less hunger.

How do I preserve muscle during weight loss?

Eat 1.6-2.2g protein per kg body weight. Do resistance training 3-4x/week. Keep deficit moderate (500 max). Sleep 7-9 hours. Slow loss preserves more muscle than crash dieting.

How many calories in 1 kg of body fat?

About 7,700 calories. To lose 1 kg/week: 7,700/7 = 1,100 cal/day deficit. That is aggressive. A 500 cal/day deficit = 0.45 kg/week, which is safer and more sustainable.

Calorie Deficit Calculator - Free Weight Loss Calculator (2026)

Your Weight Loss Plan

Personalized calorie target and timeline

Eat Per Day

2,084 cal

Daily Deficit

550 cal

Loss Rate

0.5 kg/wk

Time to Goal

20 weeks

Progress Timeline

80 kg20 wks70 kg

Deficit Comparison

Deficit	Daily Cal	Loss Rate	Time	Safety

// Health · ShashaTools

Calorie Deficit Calculator

Sex

Age 30

1580

Height 170 cm

120220

Current Weight 80 kg

40200

Goal Weight 70 kg

40180

Activity Level

// Advanced

Loss Rate 0.5 kg/wk

0.25 = gentle. 0.5 = standard. 0.75 = aggressive. 1.0 = maximum safe rate.

// Results

Daily Calories

2,084

TDEE

2,584 cal/day

Deficit

500 cal/day (19%)

Loss Rate

0.5 kg/week (1.1 lbs)

Time to Goal

20 weeks (140 days)

Protein Target

160g/day (640 cal)

Eat 2,084 cal/day to lose 10.0 kg in 20 weeks

How to Use This Calculator

Find your daily calorie target for sustainable weight loss

Simple Quick Plan

Enter your stats

Sex, age, height, current weight, and activity level determine your TDEE (total daily burn).

Set your goal weight

Where you want to be. The calculator finds how much you need to lose and builds a timeline.

Read your daily target

This is how many calories to eat per day. The deficit is automatically calculated for safe, sustainable loss at 0.5 kg/week.

Compare deficits

The table shows 4 deficit levels with loss rates and timelines. Choose the balance of speed vs sustainability that works for you.

💡 Golden rule: 1 kg of body fat = 7,700 calories. A 500 cal/day deficit = 3,500/week = ~0.45 kg/week. The math always works if you track accurately.

Advanced Customize

Set custom loss rate

0.25 kg/week is gentle and easy. 0.5 is the standard recommendation. 0.75-1.0 is aggressive but short-term viable.

Check the safety column

The table flags if a deficit would push you below BMR. Eating below BMR risks muscle loss and metabolic damage.

Hit your protein target

The calculator shows your protein recommendation (2g/kg). This preserves muscle during the deficit. Prioritize protein every day.

Recalculate every 5 kg

As you lose weight, your TDEE drops. Re-enter your new weight every 5 kg to get an updated calorie target.

💡 Tip: Take a 1-2 week diet break at maintenance every 8-12 weeks of deficit. This resets hormones, prevents metabolic adaptation, and makes the next phase of dieting more effective.

// Recommended Tools

ℹ️ Affiliate disclosure: Some links are affiliate links.

MyFitnessPal

Track calories and stay in your deficit target.

Get Started →

Noom

Psychology-based weight loss with calorie tracking.

Start Trial →

Food Scale

Weigh food for accurate calorie counting.

Compare →

Smart Scale

Track weight trends to verify your deficit works.

Shop →

// Related Calculators

📊

TDEE & Macro Calculator

Full macro breakdown for your deficit.

📏

Body Fat Calculator

Track body composition, not just weight.

🏋️

Calories Burned Calculator

See how exercise increases your deficit.

⚖️

BMI Calculator

Check your BMI as you lose weight.

// Complete Guide — Updated 2026

Calorie Deficit for Weight Loss:
The Complete Guide

Every diet in history works through one mechanism: creating a calorie deficit. Keto, intermittent fasting, paleo, Weight Watchers — all of them reduce calories in different ways. The deficit is the engine. The diet is just the vehicle. This guide strips away the noise and shows you how to calculate, implement, and sustain a calorie deficit that actually works.

The Core Formula

// Calorie Deficit

Target Calories = TDEE − Deficit

2,584 − 500 = 2,084 cal/day (loses ~0.45 kg/week)

// Time to Goal

Weeks = kg to lose ÷ kg lost per week

10 kg ÷ 0.5 kg/week = 20 weeks

Real-World Scenarios

Scenario 1: Standard Weight Loss. James, 30, male, 85 kg, wants to reach 75 kg. TDEE: 2,680. At 500-cal deficit: eats 2,180 cal/day, loses 0.45 kg/week, reaches goal in 22 weeks. Protein: 170g/day. He tracks in MyFitnessPal and weighs weekly. Use our TDEE Calculator for full macros.

Scenario 2: Aggressive Short-Term Cut. Maria, 28, 72 kg, needs to drop 5 kg in 8 weeks for an event. TDEE: 2,150. Deficit of 700 = 1,450 cal/day. Loss rate: 0.64 kg/week. She hits goal in 7.8 weeks. Aggressive but above BMR (1,370). She adds resistance training 4x/week to preserve muscle. Use our Body Fat Calculator to track composition.

Scenario 3: Gentle Sustainable Approach. David, 45, 95 kg, goal 80 kg. TDEE: 2,430. Gentle 250-cal deficit = 2,180 cal/day. Loses 0.23 kg/week. Takes 65 weeks. Slow, but he never feels deprived. He takes diet breaks every 12 weeks. This is the approach with the highest long-term success rate.

Scenario 4: The Plateau Breaker. Priya lost 8 kg in 16 weeks at 500-cal deficit but stalled for 3 weeks. Her body adapted. Solution: 2-week diet break at maintenance (recalculated TDEE at new weight), then resume deficit. She also dropped her activity multiplier one level to be more conservative. Weight loss resumed at 0.4 kg/week. Use our Calories Burned Calculator to verify exercise burn estimates.

💡 Key insight: The number one reason deficits fail is not the math — it is not tracking accurately. Studies show people underestimate calorie intake by 30-50%. Weigh your food. Log everything. A 500-calorie deficit on paper means nothing if you are actually eating 300 calories more than you think.

Deficit Quick Ref

250 cal/day	~0.25 kg/wk
500 cal/day	~0.45 kg/wk
750 cal/day	~0.70 kg/wk
1000 cal/day	~0.90 kg/wk

1 kg fat = ~7,700 calories

// Frequently Asked Questions

Common Questions About Calorie Deficit

What is a calorie deficit? +

Eating fewer calories than you burn. A 500 cal/day deficit loses about 0.45 kg/week. The only mechanism for fat loss regardless of diet type.

How big should my deficit be? +

250-500 for sustainable loss. 500-750 for faster results. Never below BMR. Larger deficits risk muscle loss, fatigue, and metabolic slowdown.

How many calories to lose weight? +

TDEE minus 500. For most: women 1,200-1,500, men 1,500-1,800 for active loss. Our calculator gives your personalized number.

How long to lose 10 kg? +

At 0.5 kg/week: 20 weeks (5 months). At 0.75 kg/week: 13 weeks (3 months). Slower is more sustainable and preserves muscle.

Will a 1000 cal deficit work? +

Loses weight fast (~1 kg/week) but risks muscle loss, fatigue, deficiency, and metabolic adaptation. Only short-term viable. 500-750 is safer.

Why am I not losing weight? +

Likely underestimating intake. Track every bite for a week. Other causes: water retention, metabolic adaptation, or TDEE estimate too high.

Eat less or exercise more? +

Both. Diet creates the deficit, exercise preserves muscle. 300 cal diet cut + 200 cal exercise = 500 total with less hunger.

What is metabolic adaptation? +

Metabolism slows during prolonged deficit. Take 1-2 week diet breaks at maintenance every 8-12 weeks to reset hormones and prevent plateaus.

How to preserve muscle? +

Eat 1.6-2.2g protein/kg. Lift weights 3-4x/week. Keep deficit moderate (500 max). Sleep 7-9 hours. Slow loss preserves more muscle.

How many calories in 1 kg fat? +

About 7,700 calories. A 500 cal/day deficit = 3,500/week = ~0.45 kg/week. A 1,100 cal/day deficit = 1 kg/week (aggressive but mathematically accurate).

Calorie DeficitCalculator

Calorie Deficit for Weight Loss:The Complete Guide

The Core Formula

Real-World Scenarios

Calorie Deficit
Calculator

Calorie Deficit for Weight Loss:
The Complete Guide