A healthy goal weight for an adult is one that gives a BMI of 18.5 to 24.9, and a safe pace is 0.5 to 2 lb (0.25 to 1 kg) a week. At a pound a week, losing 20 lb takes about 20 weeks — roughly five months — with a deficit of around 500 calories a day. The first 5% of your weight brings the biggest health gains, so it is a good first target.
Enter your height, your weight now and your goal — or leave the goal blank to aim for the edge of the healthy range. The calculator gives the date you could reach it, your goal BMI and the milestones on the way.
Worked example
Height: 5 ft 9 inWeight now: 190 lbGoal weight: 165 lbPace: Steady — 1 lb (0.45 kg) a week
Reach 165 lb by: April 24, 2027 Goal BMI 24.4 · Healthy weight
Losing 25 lb at a pound a week takes 25 weeks — about six months — and needs a deficit of roughly 500 calories a day. The goal of 165 lb is a BMI of 24.4, inside the healthy range at 5 ft 9 in; the first milestone, 5% of body weight (9.5 lb), comes after about ten weeks.
Open this example in the calculator →How to use the Goal Weight Calculator
- Choose US or metric units and enter your height and current weight.
- Enter a goal weight, or leave it blank to aim for the nearest edge of the healthy range.
- Pick a pace — 1 lb (0.45 kg) a week is a good default.
- Read the date you would reach your goal, your goal BMI and the milestones on the way.
How to choose a goal weight
- Start with 5 to 10%. Losing 5% of body weight improves blood pressure, blood sugar and cholesterol for many people, and 10% brings more. For someone who weighs 200 lb, that is 10 to 20 lb — a goal that does not depend on reaching any chart.
- Use the healthy range as the long-term guide. Any weight that gives a BMI of 18.5 to 24.9 is a healthy weight for an adult. The healthy weight calculator shows yours.
- Check your waist. A waist under half your height is a sign that the weight you are at is a healthy one, whatever the scale says.
How long does it take to lose weight?
| To lose | At 0.5 lb a week | At 1 lb a week | At 2 lb a week |
|---|---|---|---|
| 10 lb (4.5 kg) | 20 weeks | 10 weeks | 5 weeks |
| 20 lb (9 kg) | 40 weeks | 20 weeks | 10 weeks |
| 30 lb (13.6 kg) | 60 weeks | 30 weeks | 15 weeks |
| 50 lb (22.7 kg) | 100 weeks | 50 weeks | 25 weeks |
These are planning figures. Expect the first week or two to go faster (much of it is water) and the later weeks slower.
The 500-calorie rule, and why loss slows
A pound of body fat holds about 3,500 calories, so a deficit of 500 calories a day has long been taken to lose a pound a week. That is a fair start, but it overstates loss over months: a lighter body burns fewer calories, so the same diet produces a smaller deficit as you go. Researchers at the NIH, led by Kevin Hall, showed in 2011 that the real curve flattens, and built the Body Weight Planner on their model. A practical answer is to recheck your calorie needs every 10 lb or so with the calorie calculator.
Is 2 lb a week too fast?
Up to 2 lb (about 1 kg) a week is the upper end of what US and UK guidelines describe as safe for most adults, and is more realistic for people with a lot to lose. Faster loss is usually done only under medical supervision, for example with a very-low-calorie diet. Losing faster than you planned without trying is a reason to see a doctor.
Keeping it off
Most weight regain happens in the first year. Regular physical activity — around 150 to 300 minutes of moderate activity a week — strength training to keep muscle, regular weighing and enough sleep are the habits most consistently linked with keeping weight off.
Frequently asked questions
What should my goal weight be?
For most adults, a weight within the healthy BMI range for your height (a BMI of 18.5 to 24.9) is a good long-term goal, and 5 to 10% of your current weight is a good first one. At 5 ft 9 in the healthy range is 125 to 168 lb.
How long will it take to lose 20 pounds?
About 20 weeks at 1 lb a week, or 10 weeks at 2 lb a week. In practice it usually takes a little longer, because weight loss slows as you get lighter.
How many calories should I cut to lose a pound a week?
About 500 calories a day below what you burn. The calorie calculator estimates what you burn from your size, age and activity.
Is losing 2 pounds a week safe?
For most adults with weight to lose, up to 2 lb (about 1 kg) a week is considered safe. Lighter people, older adults and anyone with a medical condition should aim lower, and faster loss needs medical supervision.
Why has my weight loss slowed down?
As you lose weight, your body needs fewer calories, so the deficit you started with shrinks. Water shifts can also hide fat loss for a week or two. Recalculate your calorie needs at your new weight.
Can I use this calculator to gain weight?
Yes. Enter a goal above your current weight. For someone underweight, a gain of about 0.5 to 1 lb a week with enough protein and some strength exercise is a common target.
Sources
- Adult BMI Categories — Centers for Disease Control and Prevention
- Calculate Your Body Mass Index — National Heart, Lung, and Blood Institute (NIH)
- Hall KD et al. Quantification of the effect of energy imbalance on bodyweight. Lancet 2011;378:826–837 — The Lancet
- Body Weight Planner — National Institute of Diabetes and Digestive and Kidney Diseases (NIH)
- Overweight and obesity management (NG246), 2025 — National Institute for Health and Care Excellence (UK)
- Dietary Guidelines for Americans, 2020–2025 — U.S. Department of Agriculture and HHS
For general information only — not a diagnosis or a substitute for advice from a doctor. How we calculate.