A calorie deficit is eating fewer calories than your total daily energy expenditure (TDEE). To lose about 1 lb (0.45 kg) a week, subtract roughly 500 kcal a day from your TDEE; for 0.5 lb a week, about 250. Most adults do best with a deficit of 10–20% of TDEE, and no lower than 1,200 kcal (women) or 1,500 kcal (men) without medical supervision.
Key takeaways
- A deficit of about 500 kcal a day corresponds to roughly 1 lb (0.45 kg) a week at the start, then loss slows as your body gets smaller.
- For the example 35-year-old woman (TDEE 2,239 kcal), a 1 lb a week target is about 1,740 kcal, a 22% deficit; 0.5 lb a week is about 1,989 kcal.
- The calculator dates your goal with a dynamic model that lowers your TDEE as you lose weight, so it is more realistic than the flat 3,500-kcal rule.
- Deficits above about 25% of TDEE, or targets below your BMR or the 1,200/1,500 kcal floors, call for a doctor or registered dietitian.
How this calorie deficit calculator works
Enter your sex, age, weight, height, activity level and goal weight, then choose a pace of 0.5, 1, 1.5 or 2 lb a week (0.25 to 1 kg in metric). The calculator estimates your TDEE with the Mifflin–St Jeor equation (Mifflin et al., 1990) and subtracts the daily deficit that pace requires.
It shows your daily target, the deficit in kcal and as a percentage of TDEE, and an estimated goal date. A table lists every pace side by side, and it warns you if a target falls below your BMR, below 1,200 kcal (women) or 1,500 kcal (men), or if the deficit exceeds 25% of TDEE. If you only want a target date or a projection, use the weight loss calculator.
How many calories do I need to cut to lose weight?
The working formula is simple:
Daily deficit = pounds per week × 3,500 ÷ 7 (or kg per week × 7,700 ÷ 7) Target calories = TDEE − daily deficit
So 1 lb a week is a 500 kcal deficit, 1.5 lb is about 750 and 2 lb is about 1,000. Here is what that means for two example adults, both moderately active (×1.55):
| Pace | Woman, 35, 5′5″, 165 lb: target | % below TDEE | Man, 30, 5′10″, 190 lb: target | % below TDEE |
|---|---|---|---|---|
| Maintenance | 2,239 kcal | 0% | 2,834 kcal | 0% |
| 0.5 lb/week | 1,989 kcal | 11% | 2,584 kcal | 9% |
| 1 lb/week | 1,740 kcal | 22% | 2,335 kcal | 18% |
| 1.5 lb/week | 1,490 kcal | 33% | 2,085 kcal | 26% |
| 2 lb/week | 1,241 kcal | 45% | 1,836 kcal | 35% |
Her BMR is 1,444 kcal and his is 1,828 kcal. For her, the 1.5 lb row is barely above BMR and the 2 lb row is well below it, only 41 kcal above the 1,200 kcal floor. For him, the 2 lb row is almost exactly his BMR and a 35% deficit. Those rows are too aggressive for most people.
How big should a calorie deficit be?
The TDEECalc app’s presets use 10%, 15% and 20% below TDEE, a range that for most people is easier to sustain while keeping muscle and energy up. A 15% deficit for the example woman is about 1,903 kcal, roughly 0.7 lb a week at first.
Larger deficits lose weight faster but cost more in hunger, training performance and lean mass. If you have less to lose, or you lift weights, a smaller deficit with adequate protein (see the protein calculator) is the better trade (Jäger et al., 2017). For the step-by-step method, see how to use TDEE to lose weight.
Why the goal date is not 3,500 kcal per pound
The old rule says a pound of fat is 3,500 kcal, so a 500 kcal daily deficit loses a pound a week indefinitely. Dynamic models show this overstates long-term loss, because a lighter body burns less and the deficit shrinks as you progress (Hall et al., 2011; Thomas et al., 2014).
TDEECalc recalculates your TDEE every week from your lower body weight and holds your calorie intake fixed at the target. For the example woman, a 1 lb a week target (1,740 kcal) to lose 20 lb (165 to 145 lb) takes about 24 weeks, not the 20 the flat rule predicts. At 0.5 lb a week it takes about 59 weeks, not 40. Faster deficits show a smaller gap, because less time passes before you arrive.
This is a planning model, not a prediction. The NIDDK Body Weight Planner uses a more detailed version of the same idea (NIDDK Body Weight Planner). Real results also depend on adherence and on adaptive changes in expenditure (Rosenbaum & Leibel, 2010).
What are the safe minimums?
- Floor: about 1,200 kcal a day for women and 1,500 kcal for men, unless a clinician supervises.
- BMR: avoid planning below your BMR for long. It is the energy you burn lying still all day. See the BMR calculator.
- Size of deficit: the calculator warns above 25% below TDEE, because deficits that large are hard to sustain and hard to fuel well.
- See a professional first if you are pregnant or breastfeeding, under 18, have a history of disordered eating, or take diabetes medication.
Dietary guidance for Americans frames weight management as a long-term pattern, not a crash diet (Dietary Guidelines 2020–2025). Aim for a deficit you could hold for 8–12 weeks, then take a maintenance break.
What if my result does not match the scale?
Equations estimate an average person, so your true maintenance can sit 10% or more away from your TDEE estimate. Log your weight and calories for a few weeks and compare. If the scale disagrees, adjust intake by about 100–200 kcal toward the real trend, or measure your maintenance directly with the adaptive TDEE calculator. For background, see the calorie deficit guide and how many calories to eat.
Frequently asked questions
How many calories should I cut to lose 1 pound a week?
About 500 kcal a day below your TDEE, based on the common figure of roughly 3,500 kcal per pound of body weight change. Treat it as a starting point: as you lose weight your TDEE falls, so the same intake produces a smaller deficit and slower loss over time.
Is a 500 calorie deficit enough?
For many people, yes. A 500 kcal deficit is about 22% of TDEE for a 165 lb woman and about 18% for a 190 lb man, which is already at the upper end of what is easy to sustain. If you have little weight to lose, 250 kcal a day is often more realistic.
What is the minimum number of calories I should eat?
As a general floor, about 1,200 kcal a day for women and 1,500 kcal for men, and never below your BMR for long. Lower intakes should only happen under medical supervision, because they make it hard to meet protein and micronutrient needs and increase muscle loss.
Why am I not losing weight in a calorie deficit?
Common causes are underestimated intake, an overestimated activity level, water retention masking fat loss, or too short a window. Compare your real trend over 2–4 weeks with the prediction. If they disagree, measure your actual maintenance with the adaptive TDEE calculator.
Should I eat back my exercise calories?
Not if your activity level already includes your workouts. Activity multipliers such as 1.55 are built from typical weekly exercise, so adding the calories again double counts them. See the calories burned calculator for how to treat extra sessions.
References
- Hall KD, Sacks G, Chandramohan D, et al. (2011). Quantification of the effect of energy imbalance on bodyweight. The Lancet 378(9793):826–837.
- Thomas DM, Gonzalez MC, Pereira AZ, Redman LM, Heymsfield SB (2014). Time to correctly predict the amount of weight loss with dieting. Journal of the Academy of Nutrition and Dietetics 114(6):857–861.
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition 51(2):241–247.
- National Institute of Diabetes and Digestive and Kidney Diseases (2024). Body Weight Planner. NIDDK, U.S. National Institutes of Health.
- Rosenbaum M, Leibel RL (2010). Adaptive thermogenesis in humans. International Journal of Obesity 34(Suppl 1):S47–S55.
- Jäger R, Kerksick CM, Campbell BI, et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition 14:20.
- U.S. Department of Agriculture and U.S. Department of Health and Human Services (2020). Dietary Guidelines for Americans, 2020–2025 (9th ed.). DietaryGuidelines.gov.