Calorie Deficit Calculator
Estimate your calorie deficit with our free dietary calculator. See reference ranges, risk factors, and next-step guidance.
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
Adjust values & calculateEnter your values below. Every result is computed in your browser — no data is sent to any server.
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?
A calorie deficit means your daily intake is lower than the calories you burn. Over time, that energy gap encourages weight loss, although the real-world pace varies because water balance, activity, and metabolic adaptation all affect scale weight.
How large should a deficit be?
Many adults start with a 250 to 500 calorie daily deficit because it is easier to sustain than a crash diet. Faster loss rates can be useful for some users, but the calorie target still needs to stay at a realistic and safe level.
Why does weight loss slow down over time?
As body weight drops, maintenance calories usually drop too. That means the same calorie target creates a smaller deficit later in the process, so progress often slows unless intake, activity, or both are adjusted.
Should I eat back exercise calories?
If your TDEE estimate already uses an activity multiplier, most planned exercise is already included. In that case, it usually makes more sense to watch progress over a couple of weeks rather than eating back every workout estimate.
What if my calorie target falls below a practical minimum?
That is usually a sign to slow the rate of loss, increase activity, or accept a longer timeline. Extremely low targets are hard to sustain and can make training, recovery, and day-to-day energy worse.
Where does the rule of roughly 3,500 calories per pound come from?
It is derived from the energy density of adipose tissue, which is mostly lipid at about nine calories per gram, applied to a pound of that tissue. As a rough conversion it is serviceable for a first estimate over a few weeks. Over months it systematically overpredicts loss, because it assumes maintenance never changes, ignores the water and glycogen that move early on, and treats every pound lost as pure fat.
Why can scale weight rise during a week I was clearly in a deficit?
Because most short-term weight movement is fluid, not tissue. Each gram of stored glycogen holds roughly three grams of water with it, so a higher-carbohydrate day adds weight without adding fat. Sodium intake, gut contents, hormonal fluctuation across the menstrual cycle, and inflammation after hard training all shift the reading by more than a week of genuine fat loss would. A weekly average is the only figure worth reacting to.
Should the deficit be set as a fixed number or a percentage?
A fixed calorie deficit is simple but scales badly: 500 calories is a modest cut for a large person and an aggressive one for a small one. Setting the deficit as a percentage of maintenance keeps the aggressiveness comparable across body sizes and automatically shrinks in absolute terms as maintenance falls. Percentage-based targets tend to be the safer default for lighter individuals, where a fixed cut can push intake uncomfortably low.
How does protein intake change what a deficit costs you?
A deficit forces the body to cover the shortfall from stored tissue, and without sufficient protein and a training stimulus part of that comes from muscle rather than fat. Losing lean tissue lowers resting expenditure, which makes holding the result harder afterwards. Raising protein during a deficit also helps with satiety, which makes the target easier to hit consistently. The deficit sets how fast weight moves; protein and training influence which tissue moves.
How do I tell whether the maintenance estimate itself was wrong?
Track intake accurately and average body weight over two to three weeks, then compare the observed rate of change with what the deficit predicted. Consistently losing faster than planned means maintenance was underestimated; consistently slower means it was overestimated, or that intake tracking is drifting. Adjust the maintenance figure to match observed reality rather than reflexively cutting calories, since the estimate is the assumption most likely to be wrong.
References
Reviewed for accuracy by Rahul Singh, Health & Wellness Specialist · Editorial policy
Related Calculators
🧮Basal Metabolic Rate Calculator
Estimate BMR, compare common metabolic formulas, and turn the result into practical daily calorie targets.
🧮Body Composition Change Predictor
Project fat mass, lean mass, and body-fat changes from calorie intake, maintenance calories, protein intake, and timeline assumptions.
🧮Adjusted Body Weight Calculator
Estimate ideal body weight, adjusted body weight, and dosing-weight comparisons for obesity-aware medication and nutrition planning.
🧮RMR Calculator
Estimate resting metabolic rate, compare common metabolic formulas, and turn the result into calorie targets for loss, maintenance, or gain.
🧮Weight Gain Calculator
Estimate calorie surplus, macro targets, and a realistic timeline for healthy weight gain or a lean bulk.
🧮Weight Watchers Points Calculator
Estimate SmartPoints-style food values from calories, saturated fat, sugar, protein, servings, and a daily budget target.
🧮Body Recomposition Calculator
Estimate goal weight, calorie targets, fat loss pace, and macro guidance for a body recomposition phase.
🧮TDEE Calculator
Calculate Total Daily Energy Expenditure