How to Calculate Your Calorie Deficit for Weight Loss (With Examples)

What Is a Calorie Deficit?

A calorie deficit occurs when you consume fewer calories than your body burns in a day. This forces your body to use stored energy — primarily body fat — to make up the difference, resulting in weight loss over time.

The concept is simple: if your body needs 2,200 calories per day to maintain its current weight and you eat 1,700 calories, you create a 500-calorie deficit. Over 7 days, that adds up to 3,500 calories — roughly equivalent to 0.45kg (1 pound) of body fat.

How to Calculate Your Calorie Deficit

Step 1: Find your TDEE (Total Daily Energy Expenditure)

Your TDEE is the total number of calories your body burns in a day, accounting for your basal metabolic rate (BMR) and activity level. Use our Calorie Deficit Calculator to find yours instantly.

The Mifflin-St Jeor equation is the most accurate formula for estimating BMR:

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

Your TDEE multiplies BMR by an activity factor:

• Sedentary (desk job, little exercise): BMR × 1.2
• Lightly active (1–3 days exercise): BMR × 1.375
• Moderately active (3–5 days exercise): BMR × 1.55
• Very active (6–7 days exercise): BMR × 1.725

Step 2: Subtract your target deficit

A safe and sustainable calorie deficit is between 300 and 700 calories below your TDEE:

• 300–500 calorie deficit: slow, sustainable loss (0.25–0.5kg per week)
• 500–700 calorie deficit: moderate loss (0.5–0.7kg per week)
• 1,000+ calorie deficit: aggressive — not recommended without medical supervision

Step 3: Calculate your daily calorie target

Daily Calorie Target = TDEE − Deficit

Example: A 35-year-old woman, 65kg, 165cm, moderately active has a TDEE of approximately 2,100 calories. A 500-calorie deficit gives a daily target of 1,600 calories.

How Big Should Your Calorie Deficit Be?

The right deficit depends on your starting point, timeline, and lifestyle. Here are the general guidelines:

For gradual, sustainable loss: 300–500 calories below TDEE. You will lose 0.25–0.5kg per week. This approach preserves muscle mass and is easier to maintain long-term.

For faster results: 500–750 calories below TDEE. You will lose approximately 0.5–0.75kg per week. Still considered safe for most people if nutritional needs are met.

What to avoid: Deficits larger than 1,000 calories per day are associated with muscle loss, nutritional deficiencies, fatigue, and metabolic adaptation (where your body slows down to compensate).

Calorie Deficit by Goal: Real Examples

Example 1 — Losing 5kg in 10 weeks To lose 5kg you need to burn approximately 38,500 calories more than you consume. Over 10 weeks (70 days) that requires a daily deficit of 550 calories. If your TDEE is 2,000, target 1,450 calories per day.

Example 2 — Losing 10kg over 6 months 10kg requires approximately 77,000 calories deficit over 26 weeks (182 days) — about 423 calories per day. A modest deficit that is sustainable for most people.

Example 3 — Maintenance after reaching goal weight Once you reach your target weight, return to eating at your TDEE. Use our Calorie Calculator to find your new maintenance calories (your TDEE changes as your weight changes).

Common Calorie Deficit Mistakes

Underestimating calorie intake. Research consistently shows people underestimate how many calories they eat by 20–40%. Weigh food where possible rather than estimating portions.

Overestimating calorie burn from exercise. Fitness trackers can overestimate calories burned by 20–90%. Do not eat back all exercise calories immediately.

Cutting too aggressively. Extreme deficits lead to muscle loss, hormonal disruption, and unsustainable hunger. Slower is almost always better for long-term results.

Not adjusting as weight changes. As you lose weight your TDEE decreases. Recalculate every 4–6 weeks to ensure you are still in a deficit.

Ignoring protein intake. In a calorie deficit, protein becomes more important — not less. Aim for at least 1.6–2g of protein per kg of bodyweight to preserve muscle. Use our Macro Calculator to set your targets.

How Long Will It Take to Reach My Goal?

Use this simple formula:

Weeks to goal = (kg to lose × 7,700) ÷ daily calorie deficit

Examples:

• Lose 5kg with a 500 cal/day deficit: (5 × 7,700) ÷ 500 = 77 days ≈ 11 weeks
• Lose 10kg with a 500 cal/day deficit: (10 × 7,700) ÷ 500 = 154 days ≈ 22 weeks
• Lose 3kg with a 300 cal/day deficit: (3 × 7,700) ÷ 300 = 77 days ≈ 11 weeks

Our Target Weight Calculator does this calculation automatically.

Frequently Asked Questions

• Is 500 calories a day deficit safe?

Yes, for most healthy adults a 500-calorie daily deficit is considered safe and sustainable. It produces approximately 0.5kg of weight loss per week, which is within the range recommended by most health authorities.

• Can I create a calorie deficit through exercise alone?

Technically yes, but it is difficult to sustain. Running for 45 minutes burns roughly 400–600 calories — less than many people assume. A combination of dietary changes and increased activity is the most effective approach.

• What happens if my calorie deficit is too large?

Deficits over 1,000 calories per day can cause muscle loss, nutritional deficiencies, extreme hunger, fatigue, and metabolic adaptation. Your body becomes more efficient at conserving energy, making further weight loss harder.

• Do I need to count calories forever?

No. Most people use calorie counting as a temporary tool to understand their eating habits. Once you have a good sense of portion sizes and calorie content, many people successfully maintain their weight without tracking.

• Should my calorie deficit be the same every day?

Not necessarily. Some people prefer a consistent daily deficit while others use a weekly average — eating at maintenance on weekends and a larger deficit on weekdays. Both approaches work as long as the weekly total is correct.