Calorie Deficit Calculator
Estimate your calorie deficit with our free dietary calculator. See reference ranges, risk factors, and next-step guidance.
Reviewed for accuracy by Rahul Singh, Health & Wellness Specialist
Medical disclaimer: This calculator is provided for educational and informational purposes only and does not constitute medical advice, diagnosis, or treatment. Results are general estimates and may not reflect your individual circumstances. Always consult a qualified healthcare professional before making decisions about your health.
Calorie Deficit Calculator
Calculator
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Formula: Daily Calories = TDEE - Deficit
Worked example — Target: 2,403 cal/day | 30 weeks to goal | Deficit: 500 cal/day
Formula
Daily Calories = TDEE - Deficit
Calculate TDEE using the Mifflin-St Jeor equation (BMR x Activity Factor), then subtract the daily calorie deficit based on desired weight loss rate. A deficit of 500 cal/day = ~1 lb/week loss (3,500 cal = 1 lb of fat). Weeks to goal = total weight to lose / weekly loss rate. Minimum safe intake: 1,500 cal (men), 1,200 cal (women).
Worked Examples
Example 1: Male — 30 lbs to Lose at 1 lb/week
Problem:30-year-old male, 200 lbs, 5'10" (70 inches), moderately active. Goal: 170 lbs at 1 lb/week.
Solution:Convert: 200 lbs = 90.7 kg, 70 in = 177.8 cm BMR = 10(90.7) + 6.25(177.8) - 5(30) + 5 = 907 + 1,111 - 150 + 5 = 1,873 cal TDEE = 1,873 x 1.55 = 2,903 cal Deficit: 500 cal/day for 1 lb/week Daily target: 2,903 - 500 = 2,403 cal Weight to lose: 30 lbs Weeks to goal: 30 / 1 = 30 weeks
Result:Target: 2,403 cal/day | 30 weeks to goal | Deficit: 500 cal/day
Example 2: Female — 20 lbs to Lose at 0.5 lb/week
Problem:35-year-old female, 160 lbs, 5'4" (64 inches), lightly active. Goal: 140 lbs at 0.5 lb/week.
Solution:Convert: 160 lbs = 72.6 kg, 64 in = 162.6 cm BMR = 10(72.6) + 6.25(162.6) - 5(35) - 161 = 726 + 1,016 - 175 - 161 = 1,406 cal TDEE = 1,406 x 1.375 = 1,933 cal Deficit: 250 cal/day for 0.5 lb/week Daily target: 1,933 - 250 = 1,683 cal Weight to lose: 20 lbs Weeks to goal: 20 / 0.5 = 40 weeks
Result:Target: 1,683 cal/day | 40 weeks to goal | Deficit: 250 cal/day
Example 3: Moderate one-pound-per-week plan
Problem:A 30-year-old male weighs 200 lbs, wants to reach 170 lbs, and trains at a moderate activity level.
Solution:Estimated TDEE is about 2,900 calories per day. A 500-calorie deficit sets a target near 2,400 calories per day. Losing 30 lbs at about 1 lb per week gives a rough timeline of 30 weeks.
Result:Target: about 2,400 cal/day | Timeline: about 30 weeks
Frequently Asked Questions
What is a calorie deficit and how does it cause weight loss?
A calorie deficit occurs when you consume fewer calories than your body burns (your TDEE). Your body must then access stored energy — primarily body fat — to make up the difference. One pound of body fat stores approximately 3,500 calories of energy, so a daily deficit of 500 calories theoretically produces one pound of fat loss per week (500 x 7 = 3,500). However, weight loss is not perfectly linear because the body also loses some water and lean tissue, metabolism adapts slightly over time, and hormonal fluctuations cause water retention. Despite these variations, a sustained calorie deficit is the fundamental requirement for weight loss, regardless of the specific diet approach used.
What is a safe calorie deficit for weight loss?
A safe calorie deficit is generally 500-750 calories below TDEE, producing 1-1.5 pounds of weight loss per week. Health organizations recommend that men should not consume below 1,500 calories per day and women below 1,200 calories per day without medical supervision. Larger deficits (1,000+ calories) may be appropriate for individuals with a BMI above 30 under medical guidance, as they have more energy reserves to safely draw from. Overly aggressive deficits cause muscle loss, metabolic adaptation (your body burns fewer calories), nutrient deficiencies, hormonal disruption, fatigue, and increased risk of binge eating. A moderate, sustainable deficit produces better long-term results than crash dieting.
How accurate is the 3,500 calories per pound rule?
The 3,500-calorie rule is a widely cited simplification that provides a useful starting estimate but is not perfectly accurate for real-world weight loss predictions. Research by Dr. Kevin Hall and others has shown that this rule overestimates weight loss over time because it does not account for metabolic adaptation — as you lose weight, your TDEE decreases, reducing the effective deficit. Additionally, initial weight loss includes significant water weight (especially when reducing carbohydrates), making early results appear faster than expected. More sophisticated models like the NIH Body Weight Planner account for metabolic changes. In practice, expect weight loss to slow over time and plan to periodically recalculate your TDEE and adjust your calorie target.
Should I eat back exercise calories?
This is a nuanced question with different answers depending on your situation. If your TDEE calculation already includes your exercise (by selecting the appropriate activity level), then no, you should not eat back exercise calories because they are already factored in. If you calculated TDEE at a sedentary level and track exercise separately, you may want to eat back 50-75% of estimated exercise calories, as calorie-burn estimates from fitness trackers and exercise machines tend to overestimate by 20-50%. Not eating back any exercise calories on heavy training days can lead to excessive deficits that compromise recovery and performance. The safest approach is to use your activity-adjusted TDEE as your maintenance number and subtract your deficit from there.
What should I do when weight loss plateaus?
Weight loss plateaus are normal and expected, typically occurring every 4-6 weeks. First, verify you are actually in a plateau by tracking your weight trend over 2-3 weeks (daily weight fluctuates 2-5 lbs from water and food volume). If the trend is truly flat, several strategies can help. Recalculate your TDEE at your new lower weight, as your body now burns fewer calories. Increase non-exercise activity (walking, standing, fidgeting) to boost NEAT. Add or increase resistance training to preserve muscle mass and metabolic rate. Try a diet break of 1-2 weeks at maintenance calories to reverse metabolic adaptation and restore hormone levels. Avoid further reducing calories below safe minimums — instead, increase activity or accept a slower rate of loss.
How many calories are in each macronutrient?
Protein and carbohydrate each supply about 4 kcal per gram, fat about 9 kcal per gram, and alcohol about 7 kcal per gram. These are Atwater factors — rounded averages, not exact constants — and real absorption varies: fibre yields closer to 2 kcal per gram, sugar alcohols less again, and whole nuts deliver measurably fewer calories than their fat content implies because some remains undigested. Because fat carries more than twice the energy per gram, small measurement errors in fat move your total far more than the same error in protein or carbohydrate, so weigh oils, nut butters, and dressings rather than estimating them by eye.
How many calories should I eat to lose weight safely?
Safe, sustainable weight loss is 0.5-1% of body weight per week — for most people that is 0.5-2 pounds per week. One pound of body fat stores roughly 3,500 calories, so a daily deficit of 500 calories below TDEE produces about one pound of loss per week. Larger deficits accelerate loss but increase muscle loss, hormonal disruption, and metabolic adaptation — the body reduces TDEE by 10-15% in response to sustained large deficits. Minimum intake thresholds exist to preserve muscle and organ function: women generally should not go below 1,200 calories and men below 1,500 without medical supervision. Combining a moderate calorie deficit (300-500 calories) with resistance training best preserves muscle while losing fat, giving better body composition outcomes than diet alone.
How does exercise intensity affect calorie burn?
Exercise intensity and calorie burn have a nuanced relationship. Higher-intensity exercise burns significantly more calories per minute — a 155 lb person burns roughly 400 calories/hour walking at 3.5 mph, 600 calories/hour jogging at 5 mph, and 900 calories/hour running at 8 mph. High-intensity interval training (HIIT) produces a meaningful excess post-exercise oxygen consumption (EPOC) or afterburn effect: metabolism remains elevated 6-15% above baseline for up to 24 hours, burning an extra 50-150 calories. However, HIIT can only be sustained 2-3 times per week before recovery suffers. Moderate-intensity steady-state cardio is sustainable daily and accumulates large total calorie expenditure over a week. The most effective approach pairs regular moderate-intensity sessions with 1-2 HIIT sessions weekly, adapted to your current fitness level.
References
Reviewed for accuracy by Rahul Singh, Health & Wellness Specialist · Editorial policy
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