Calorie deficit calculator
How many calories should you eat to lose weight? Put in a few numbers and see what you burn in a normal day, a daily target for your pace, and when you could reach your goal. Free, no account, and nothing you type leaves this page.
Your numbers
Want a plan that adjusts as you go? Glidna logs your meals from a photo or a sentence, checks this estimate against your real weigh-ins, and moves your target when it's off. Free for 30 days.
Try GlidnaHow the numbers are worked out
1. What you burn at rest
The calculator uses the Mifflin-St Jeor equation, the one dietitians use most often:
10 × weight in kg + 6.25 × height in cm − 5 × age + 5 for men, and the same with − 161 at the end for women.
2. What you burn in a normal day
That resting number is multiplied by your activity level. The result is your maintenance: eat this much and your weight should stay about the same.
| Activity level | Multiply by |
|---|---|
| Sedentary: desk or driving job, sitting most of the day (under 5,000 steps) | 1.2 |
| Lightly active: some walking and errands, on your feet now and then (5,000 to 7,500 steps) | 1.375 |
| Moderately active: on your feet most of the day: retail, nursing, teaching (7,500 to 11,000 steps) | 1.55 |
| Very active: physical job: lifting, carrying, climbing (11,000 to 15,000 steps) | 1.725 |
| Extremely active: hard labour all day: roofing, farming, heavy loads (15,000+ steps) | 1.9 |
3. Your daily target
A pound of body fat is about 3,500 calories. So ½ lb a week is 250 calories a day under maintenance, 1 lb is 500, and 2 lb is 1,000.
4. The 1,200 floor
The target never goes under 1,200 calories a day. If your pace would need less, the target stays at 1,200 and the page tells you two things: the pace 1,200 really gives you, and how many calories a day would have to come from moving more to make up the rest.
5. Your goal date
A lighter body burns less, so your maintenance drops as the weight comes off. The date is worked out a week at a time, recounting your maintenance and target at each new weight. That makes it later, and more honest, than dividing the pounds by your pace. If the goal is more than five years away, or under the healthy range for your height, the page says so instead of giving a date.
These are the same formulas the Glidna app uses for its own targets.
Questions people ask
How many calories should I eat to lose weight?
Start from your maintenance calories, the number you burn in a normal day, and eat less than that. About 500 calories a day under maintenance loses about 1 pound a week. The calculator above works out your maintenance from your age, height, weight and how active you are.
How big a calorie deficit do I need to lose 1 pound a week?
About 500 calories a day. A pound of body fat is roughly 3,500 calories, and 500 a day for 7 days is 3,500. For half a pound a week it's about 250 a day.
How many calories should I eat to lose 2 pounds a week?
About 1,000 calories a day under your maintenance. For many people, especially smaller or less active ones, that would mean eating under 1,200 a day. This calculator never sets a target under 1,200, so it tells you how much of the 2 pounds would have to come from moving more instead.
Why won't this calculator go below 1,200 calories a day?
Under 1,200 a day it gets hard to eat enough protein, vitamins and minerals, and it should only happen with a doctor watching. So when your pace would need a lower number, the target stays at 1,200 and the page shows the pace you'd really get.
How accurate is a calorie deficit calculator?
It's an estimate. The formula is usually within about 10 to 15% of what a person really burns. Weigh yourself for a few weeks: if you're losing faster or slower than the calculator said, your real maintenance is higher or lower than its guess.
Who shouldn't use a calorie deficit calculator?
Anyone under 18, anyone pregnant or who had a baby in the last 15 months, anyone with a medical condition or medicine that affects weight or eating, and anyone with an eating disorder now or in the past. If that's you, the calculator won't give a number. Talk to your doctor before you change how much you eat.