Free calculator
Calorie deficit calculator
Pick a goal weight and a weekly pace: the calculator shows how many calories to eat each day, how big the deficit is and roughly how long it takes. It never suggests eating less than 1,200 calories a day for women or 1,500 for men.
Your result
Eat about 1,550 calories a day
That is 480 kcal a day below your maintenance of 2,050 kcal: about 1 lb a week.
Losing 15 lb to reach 135 lb takes about 16 weeks at this pace, often a little longer, because loss slows as you get lighter.
Your pace of 1 lb a week would mean eating under 1,200 calories a day. We don’t suggest going lower without medical supervision, so the target stops at 1,200.
Losing more than about 1% of your weight a week (1.5 lb for you) makes it hard to keep your muscle. A slower pace keeps more of it, and is easier to stick to.
That goal weight means a BMI of 22.5, below the healthy range of 18.5–24.9. Please talk to a doctor before aiming that low.
Your goal weight isn’t below your current weight. To keep your weight, eat about 2,050 kcal a day; to build muscle, use the macro calculator.
Your maintenance (2,050 kcal) is already close to 1,200 kcal, so eating less isn’t a good idea. Move more instead: 2,000–3,000 extra steps a day burn about 100–150 kcal, and strength training protects your muscle.
This pace is within the range that protects muscle for your weight.
How the deficit is calculated
- Your maintenance calories (TDEE) with the Mifflin-St Jeor equation and your activity level, as in the TDEE calculator.
- The daily deficit: about 3,500 kcal equals 1 lb of body fat (7,700 kcal per kg), so a deficit of 500 kcal a day loses about 1 lb a week.
- The floor: the target never goes below 1,200 kcal a day for women or 1,500 for men, the usual lower limit without medical supervision.
Why weight loss slows down
The 3,500-calorie rule is a good start but too optimistic over months: as you lose weight you burn less, so the same intake loses less each week. Research models of this effect expect slower progress than the simple rule. When your loss stalls for 2–3 weeks, recalculate with your new weight, or add steps instead of cutting more food. For a detailed forecast, try the NIH Body Weight Planner.
A safe pace
- Aim for about 0.5–1% of your body weight a week. In a study of athletes, the slower rate kept more muscle and strength.
- Eat plenty of protein (protein calculator) and keep lifting: that tells your body to keep its muscle while fat goes.
- Crash diets backfire: you lose muscle and energy, and the weight tends to come back.
- Pregnant, breastfeeding, under 18 or managing a health condition? Ask your doctor before dieting.
Sources
- Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826–837. doi.org/10.1016/S0140-6736(11)60812-X
- National Institute of Diabetes and Digestive and Kidney Diseases. Body Weight Planner. www.niddk.nih.gov/bwp
- Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab. 2011;21(2):97–104. doi.org/10.1123/ijsnem.21.2.97
- Harvard Health Publishing. Calorie counting made easy. www.health.harvard.edu/staying-healthy/calorie-counting-made-easy
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241–247. doi.org/10.1093/ajcn/51.2.241
More free calculators
- TDEE calculator Your maintenance calories: how much you burn in a day.
- Macro calculator Daily calories, protein, carbs and fat for your goal.
- Protein calculator How much protein you need a day, and per meal.
- One-rep max calculator Estimate your 1RM from any set of 1–12 reps.
For healthy adults 16 and older. This is general information, not medical advice.