Calorie Deficit Calculator for Weight Loss (Goal + Timeline)

Calorie Deficit Calculator

Enter your goal weight and how many weeks you want to take. We'll show how many calories to eat each day and whether that pace is realistic.

Last updated September 24, 2026

Your details

Units

US (lb)UK (st)Metric (kg)

Sex

FemaleMale

Age

Weight

Height

Activity level

Goal weight

In how many weeks?

Eat about this much each day

1,390calories

That’s a deficit of about 440 calories a day below your maintenance of 1,830, to lose 14 lb in 16 weeks (about 0.9 lb a week).

An estimate using the rough rule of 3,500 calories per pound (7,700 per kg). Weight loss usually slows over time, so expect it to take longer.

Not medical advice. If you have kidney disease, diabetes, or take prescription medication, talk to your doctor or a registered dietitian before changing your protein intake. Read our full disclaimer.

How this calorie deficit calculator works

A calorie deficit means eating fewer calories than your body burns. This calculator works it out in three steps.

Find your maintenance calories. We estimate your resting burn with the Mifflin-St Jeor equation, then multiply it by your activity level (1.2 to 1.9).
Work out the total deficit. We take the weight you want to lose and use the rough rule of 3,500 calories per pound (7,700 per kg).
Spread it over your timeline. We divide that total by the number of days in your plan. The result is your daily deficit. Your daily target is maintenance minus that deficit.

Here's an example. Say you want to lose 10 lb (4.5 kg) in 10 weeks. That's about 35,000 calories over 70 days, or about 500 calories a day. If your maintenance is 2,200 calories, you would eat about 1,700.

Is your pace safe?

The CDC says people who lose about 1 to 2 lb (0.5 to 0.9 kg) a week are more likely to keep it off. If your plan asks for more than 2 lb a week, you'll see a warning. Try adding more weeks.

We also never suggest fewer than 1,200 calories a day for women or 1,500 for men. If your plan would go lower, we raise it and let you know the goal will take longer.

Why real results are often slower

The 3,500 calorie rule is handy but simple. Research led by NIH scientists found the body adapts slowly as you eat less, so the rule tends to overestimate weight loss over months. The NIH Body Weight Planner uses a more detailed model if you want a second view. Plan for things to take a bit longer than the number here.

Tips for a deficit you can keep

Pick a timeline that feels easy, not heroic. A smaller daily gap is simpler to live with.
Keep protein high to protect muscle and stay full. Find your target with our protein calculator.
Track your progress as a percent of your starting weight with our weight loss percentage calculator.

For a step-by-step walk-through, read our guide on how to calculate a calorie deficit.

If you are pregnant, under 18, take diabetes medicine, or have a history of eating disorders, talk to your doctor or a registered dietitian before starting a deficit.

Frequently asked questions

How big should my calorie deficit be?

The CDC says people who lose about 1 to 2 lb (0.5 to 0.9 kg) a week are more likely to keep the weight off. Using the rough rule of 3,500 calories per pound, that works out to a deficit of about 500 to 1,000 calories a day. A smaller deficit is often easier to stick with.

How does the calorie deficit calculator work?

It finds your maintenance calories with the Mifflin-St Jeor equation and your activity level. Then it takes the weight you want to lose, multiplies it by about 3,500 calories per pound (7,700 per kg), and spreads that over the number of days you picked. That gives your daily deficit.

Why does the calculator say my plan is faster than advised?

You see this warning when your goal and timeline need more than 2 lb (0.9 kg) of loss a week. That is faster than the CDC's suggested pace. Adding more weeks lowers the daily deficit and makes the plan easier to follow.

Can I lose weight faster by eating very little?

We never suggest fewer than 1,200 calories a day for women or 1,500 for men. If your plan needs less, we raise it to that floor and tell you the goal will take longer. Very low calorie diets should only be done with a doctor's help.