Calorie Deficit Calculator

One pound of body fat holds roughly 3,500 calories, so losing 1 lb per week requires a daily deficit of about 500 calories. Start by finding your TDEE — for example, a 40-year-old woman at 5'5", 165 lbs, moderately active, burns around 2,150 calories per day. Eating 1,650 calories would create that 500-calorie gap. A 30-year-old man at 5'11", 200 lbs, lightly active, might burn 2,500 calories and eat 2,000 to hit the same target. Your BMI from this calculator helps frame how aggressive to be: a BMI of 32.0 at 5'5", 190 lbs supports a 500-750 calorie deficit, while a BMI of 25.5 calls for a gentler 300-400 calorie cut. The follow-up most people want is how long it will take — at 1 lb per week, 20 lbs takes about 20 weeks. For a precise daily number, run your stats through the calorie calculator or TDEE calculator on this site.

For most adult men and many women, yes — 1,200 calories often falls below BMR and risks muscle loss, fatigue, and nutrient gaps. A 5'6" woman at 160 lbs with a BMI of 25.8 might have a BMR near 1,450 calories and a TDEE of 1,950; eating 1,200 creates a 750-calorie deficit, which is aggressive but workable short-term. A 5'10" man at 200 lbs with a BMI of 28.7 typically has a BMR around 1,850 and TDEE near 2,550 — dropping to 1,200 would be a 1,350-calorie deficit, far too steep and likely unsustainable past a week or two. A safer floor is BMR plus 200-300 calories, which usually lands between 1,400 and 1,800 for most adults. If you want to lose faster, add 30-45 minutes of brisk walking (200-300 calories) instead of cutting food further. Use the calorie calculator to find a target that keeps you above your BMR.

BMI measures total weight relative to height, not where fat sits. A 5'9" person at 165 lbs has a BMI of 24.4 — normal — but could carry a 38-inch waist, which signals visceral fat around the organs. Muscle weighs more than fat per volume, so someone with low muscle mass can look softer at a normal BMI. Waist circumference is the better check: over 40 inches for men and 35 inches for women raises health risk regardless of BMI. The fix is usually body recomposition — a small 200-300 calorie deficit plus 2-3 resistance training sessions per week. A 165 lb person eating 150 grams of protein daily and lifting three times weekly can drop 1-2 inches off the waist in 8-12 weeks with little scale movement. Track waist measurements monthly, not just weight. The BMI calculator gives you the starting number; a tape measure tells the fuller story.

Water weight drops first — often 2-4 lbs in the first week from reduced sodium and glycogen. Real fat loss shows on the scale by week 2-3 at a rate matching your deficit: 500 calories daily equals about 1 lb per week. A 200 lb person at a BMI of 29.9 cutting 500 calories could realistically hit 190 lbs in 10 weeks, though plateaus are common around weeks 6-8 as TDEE falls with body weight. Expect the mirror and waistband to lag the scale by 3-4 weeks. Take progress photos every two weeks and measure your waist monthly. If the scale stalls for three straight weeks while you're consistent, recalculate your TDEE — a 10 lb loss lowers daily burn by roughly 50-100 calories. The TDEE calculator helps you re-set your target after each 5-10 lb milestone.

Use both, but body fat percentage is more precise for setting calorie targets. BMI at 5'10", 185 lbs is 26.5 — overweight — yet if body fat is 15%, you're lean and a deficit would cost muscle. If body fat is 28%, a 500-calorie deficit is appropriate. Body fat ranges: men 10-20% is fit, 20-25% is average, over 25% is high; women 18-28% is fit, 28-33% is average, over 33% is high. A 5'5" woman at 150 lbs with 30% body fat (BMI 25.0) should target a 400-500 calorie deficit, while the same BMI at 22% body fat calls for maintenance plus strength training. BMI is free and instant; body fat needs a DEXA scan ($75-$150) or a reliable scale. Start with BMI from this calculator, then refine with a body fat estimate. The calorie calculator converts either into a daily intake number.

They're the same idea measured against different baselines. A calorie deficit is any shortfall between what you eat and what you burn; a TDEE deficit specifically measures that shortfall against your Total Daily Energy Expenditure. If your TDEE is 2,400 calories and you eat 1,900, your deficit is 500 calories — 21% below TDEE. Eating 1,900 when your BMR is 1,600 and TDEE is 2,400 is safe; eating 1,900 when your TDEE is 2,000 is a 100-calorie deficit that yields only 0.2 lbs per week. The common mistake is comparing intake to BMR instead of TDEE — a 1,600-calorie intake against a 1,600 BMR looks like zero deficit but is actually a 800-calorie deficit against a 2,400 TDEE. Always anchor to TDEE. This BMI tool gives your category; the TDEE calculator gives the burn number you subtract from. Pair them for an accurate daily target.