How Long Will It Take to Lose Weight? Goal Date Calculator
Short answer: at a 20% calorie deficit most people lose about 0.2 to 0.55 kg (0.5 to 1.2 lb) a week, so 5 to 10 kg takes roughly 3 to 8 months. Your own date depends on your size, age and how much you move. Enter your numbers below.
This is the same forecast the ego app shows during onboarding, with the same calorie rules. It runs in your browser; nothing you type is sent anywhere.
How the calculator works
It estimates the calories you burn in a day with the Mifflin-St Jeor equation (Mifflin et al., American Journal of Clinical Nutrition, 1990), which uses your sex, age, height and weight, then multiplies it by your activity level: 1.2 for mostly sitting up to 1.725 for very active.
To lose weight it sets your daily calories at 80% of that burn, a 20% deficit. To gain, it adds 10%. Calories never go below 1,500 a day. The gap between burn and target, at about 7,700 calories per kilogram (3,500 per pound), gives your weekly change. The pace is capped at 1% of your body weight a week for loss and 0.5% for gain, and the calculator counts the weeks to your goal from today.
Protein comes out at 2 grams per kilogram for loss or gain (1.8 to maintain). Above a BMI of 25 it uses the weight you'd have at a BMI of 25, because protein needs follow muscle, not fat.
Example dates
Calculated from October 28, 2026 with the rules above.
| Profile | Daily calories | Pace per week | Weeks |
|---|---|---|---|
| Woman, 35, 165 cm, 75 → 68 kg, lightly active | 1,590 | 0.36 kg (0.8 lb) | 20 |
| Woman, 28, 160 cm, 62 → 57 kg, active | 1,636 | 0.37 kg (0.8 lb) | 14 |
| Woman, 30, 170 cm, 70 → 63 kg, desk job | 1,500 (minimum) | 0.22 kg (0.5 lb) | 32 |
| Man, 30, 178 cm, 90 → 80 kg, desk job | 1,793 | 0.41 kg (0.9 lb) | 25 |
| Man, 40, 180 cm, 95 → 85 kg, active | 2,331 | 0.53 kg (1.2 lb) | 19 |
| Man, 25, 175 cm, 70 → 75 kg (gain), active | 2,854 | 0.24 kg (0.5 lb) | 22 |
The third row shows the minimum at work: 80% of her burn would be 1,393 calories, the plan stops at 1,500, so the deficit is smaller and the date moves out. Walking more would move it back in, which is why the activity question matters as much as the goal weight.
What this date can't know
The forecast is a straight line, and real bodies don't lose in straight lines. The first week or two often drop faster from water and glycogen. Later, you burn less as you get lighter, so the same calories make a smaller deficit. NIH researchers modeled this in Hall et al., The Lancet, 2011 and found bodyweight responds to a lasting calorie change slowly, with half-times of about a year. Their Body Weight Planner simulates that curve if you want a second opinion.
The practical fix is simple: weigh yourself a few times a week, look at the weekly average, and re-run this calculator with your new weight every few weeks. A date that moves a little is normal. A date that keeps moving out means the calories you actually eat are higher than the target, which is where logging helps.
Frequently asked questions
How long does it take to lose 10 pounds?
How fast is it safe to lose weight?
Why doesn't the calculator give me a date?
Why is my real weight loss slower than the calculator says?
Hit the calories without weighing food
ego sets these calorie and protein targets for you, logs meals from a photo, barcode or a quick chat message, and builds a strength plan to help you keep muscle while the weight comes off. Free to download on iPhone (iOS 18+); see pricing.
