Calorie Deficit Calculator
Estimate your calorie deficit with our free dietary calculator. See reference ranges, risk factors, and next-step guidance.
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\nBMR = 10(90.7) + 6.25(177.8) - 5(30) + 5 = 907 + 1,111 - 150 + 5 = 1,873 cal\nTDEE = 1,873 x 1.55 = 2,903 cal\nDeficit: 500 cal/day for 1 lb/week\nDaily target: 2,903 - 500 = 2,403 cal\nWeight to lose: 30 lbs\nWeeks 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\nBMR = 10(72.6) + 6.25(162.6) - 5(35) - 161 = 726 + 1,016 - 175 - 161 = 1,406 cal\nTDEE = 1,406 x 1.375 = 1,933 cal\nDeficit: 250 cal/day for 0.5 lb/week\nDaily target: 1,933 - 250 = 1,683 cal\nWeight to lose: 20 lbs\nWeeks to goal: 20 / 0.5 = 40 weeks
Result: Target: 1,683 cal/day | 40 weeks to goal | Deficit: 250 cal/day
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 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.
How do I interpret the result?
Results are displayed with a label and unit to help you understand the output. Many calculators include a short explanation or classification below the result (for example, a BMI category or risk level). Refer to the worked examples section on this page for real-world context.
Is Calorie Deficit Calculator free to use?
Yes, completely free with no sign-up required. All calculators on NovaCalculator are free to use without registration, subscription, or payment.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.