Calorie Deficit Calculator — How Many Calories to Eat to Lose Weight Safely

To lose weight, eat fewer calories than you burn. A 500-calorie daily deficit leads to about 1 pound of weight loss per week. Calculate your TDEE (how many calories you burn), subtract 500, and that is your daily calorie target. No crash diets, no extreme restriction — just math.

Calorie Deficit Quick Reference

Based on common TDEE ranges — find your maintenance calories, then choose your deficit:

Your TDEE	250 Deficit (0.5 lb/wk)	500 Deficit (1 lb/wk)	750 Deficit (1.5 lb/wk)
1,600	1,350	~1,200 (minimum for women)	\u2717 Too low
1,800	1,550	1,300	\u2717 Too low for most
2,000	1,750	1,500	~1,250 (near minimum)
2,200	1,950	1,700	1,450
2,400	2,150	1,900	1,650
2,600	2,350	2,100	1,850
2,800	2,550	2,300	2,050
3,000	2,750	2,500	2,250

Key rule: Never go below 1,200 calories (women) or 1,500 calories (men) without medical supervision. If a 500-calorie deficit puts you below these floors, use a smaller deficit and lose weight more slowly.

The Math Behind Weight Loss

• 1 pound of body fat = approximately 3,500 calories
• 500-calorie daily deficit x 7 days = 3,500 calories/week = ~1 lb/week
• 250-calorie daily deficit = ~0.5 lb/week (slower but more sustainable)
• 750-calorie daily deficit = ~1.5 lbs/week (aggressive but manageable for many)

This math is approximate. Actual weight loss varies due to water retention, muscle changes, metabolic adaptation, and individual variation. Use these numbers as targets, then adjust based on real results over 2-4 weeks.

How to Maintain Muscle While Losing Fat

In a calorie deficit, your body burns both fat and muscle for energy. To minimize muscle loss:

1. Eat enough protein: 0.7-1.0 grams per pound of body weight per day. At 180 lbs, that is 126-180g of protein daily. Protein is the most important macronutrient in a deficit.
2. Do resistance training: Lift weights or do bodyweight exercises 3-4 times per week. The stimulus tells your body to preserve muscle and burn fat instead.
3. Keep the deficit moderate: 500-calorie deficit preserves more muscle than 1,000-calorie deficit. Aggressive cuts sacrifice muscle.
4. Sleep 7-9 hours: Sleep deprivation increases cortisol, which promotes muscle breakdown and fat storage. Poor sleep alone can reduce the proportion of weight lost as fat by 55%.

Weight Loss Timeline Estimates

Weight to Lose	At 1 lb/week	At 1.5 lbs/week	At 0.5 lb/week
10 lbs	10 weeks	7 weeks	20 weeks
20 lbs	20 weeks	13 weeks	40 weeks
30 lbs	30 weeks	20 weeks	60 weeks
50 lbs	50 weeks	33 weeks	100 weeks
75 lbs	75 weeks	50 weeks	150 weeks

These are linear projections. In reality, weight loss slows as you get lighter because your TDEE decreases. Recalculate your TDEE every 10-15 pounds to keep the deficit accurate.

Pair These Tools Together

• Calorie Calculator — calculate your TDEE and daily calorie target
• BMI Calculator — check your body mass index
• Body Fat Calculator — estimate body fat percentage
• Percentage Calculator — calculate macro percentages
• Unit Converter — convert kg to lbs, cm to inches

Honest Limitations

Calorie deficit math is an approximation. The 3,500-calories-per-pound rule is a simplification — actual energy balance involves metabolic adaptation (your metabolism slows as you lose weight), thermic effect of food, non-exercise activity thermogenesis (NEAT), and hormonal factors. Use the calculator as a starting point, then adjust based on real results. If you are losing more than 2 lbs/week consistently, you are likely losing muscle. If you are not losing at all after 3-4 weeks of consistent tracking, reduce calories by 200 and reassess.