Weight loss calculator

See roughly when you could reach your goal weight, and what your weight might look like week by week along the way.

Why the curve slows down

The common rule says a 500 kcal daily deficit loses 1 lb a week, forever. Researchers at the NIH found it overestimates weight loss, because as you lose weight you burn less [1].

This calculator redoes the math every day. It estimates what you burn at that day’s weight with the Mifflin–St Jeor equation [2] and your activity level, then counts each day’s deficit toward your weight. As your weight falls, so does your deficit, and loss slows.

It doesn’t model every way the body adapts, so real progress is often a little slower. For a research-grade projection, use the NIH Body Weight Planner [1].

Why you might level off

If you keep eating the same amount, your weight moves toward the point where what you eat equals what you burn. If that point is above your goal, the calculator tells you, and shows about how much you’d need to eat to keep going.

What to eat at your goal weight

The calculator also shows your maintenance calories at your goal weight. They’re lower than your maintenance now. Maintaining weight covers how to keep it off.

Use your own trend

Weigh yourself a few mornings a week and look at the weekly average. If it’s moving slower or faster than the chart, adjust by 100–200 kcal a day. Your own trend is more accurate than any formula.

Next steps

• Calorie and macro calculator: your daily targets for protein, fat, carbs and fiber.
• Losing weight: what works and what makes it easier.

General information, not medical advice. If you have a health condition, are pregnant or take medication, check changes with your doctor.