Calorie Deficit Calculator
Find the calorie deficit that fits your goal. Enter your details and a weekly pace to see your maintenance calories, your daily calorie target, the size of the deficit, and the weekly loss to expect.
How the calorie deficit calculator works
A calorie deficit means eating fewer calories than you burn. The calculator estimates the calories you burn in a day, your maintenance level, then subtracts the deficit your chosen weekly pace needs to give a daily calorie target.
The formula
Your basal metabolic rate comes from the Mifflin-St Jeor equation and is multiplied by an activity factor to give maintenance calories. The deficit uses the rough average of about 7,700 calories per kilogram of body fat, or 3,500 per pound, so losing 0.5 kg a week needs about 550 calories a day and losing 1 pound a week needs about 500. The target never goes below 1,200 calories a day for women or 1,500 for men.
Why real weight loss is slower than the math
The 7,700 calorie figure is an average, not a law. As you get lighter your body burns less, so the same intake produces a smaller deficit over time and plateaus are normal. Recalculate every few kilograms, and judge progress over weeks rather than days.
Frequently asked questions
What is a good calorie deficit for weight loss?
For most people a deficit of roughly 300 to 500 calories a day is a sustainable starting point. That lines up with the gradual 1 to 2 pounds (about 0.5 to 1 kg) a week that public health agencies like the CDC consider safe. Bigger is not better: very large deficits are hard to sustain and cost more muscle.
How do I calculate my calorie deficit?
Estimate your maintenance calories, the amount you burn in a day, then subtract your deficit. This calculator does both steps: it works out maintenance from your sex, age, height, weight, and activity, then subtracts the deficit for the weekly pace you choose.
Is a 500 calorie deficit enough to lose weight?
Yes. By the usual rough average, 500 calories a day is about 1 pound (0.45 kg) a week. Real loss tends to run a little slower than the math, because your body burns less as you get lighter.
What is the lowest number of calories I should eat?
Many sources suggest not dropping below roughly 1,200 calories a day for women or 1,500 for men without professional supervision. The calculator caps its target at those levels, and tells you when the pace you picked would need less than that.
Why am I not losing weight in a calorie deficit?
The most common reasons are underestimating what you eat, overestimating exercise burn, and water retention hiding fat loss for a week or two. Your maintenance level also falls as you lose weight, so a deficit that worked at the start can shrink to nothing. Recheck your numbers and track your intake carefully for two weeks before changing the plan.