A BMI target turns “lose some weight” into a concrete number. Losing 0.5–1 kg (1–2 lb) a week is the pace most health services recommend, and even a 5% loss improves blood pressure and blood sugar.
How to use the BMI Weight Loss Calculator
- Weight
- Height
- Target BMI
- Weekly weight change
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter your weight, height and the BMI you are aiming for. The calculator works out your current BMI, the matching target weight and the difference, and divides the difference by your chosen weekly pace.
BMI categories
| BMI (kg/m²) | Category (WHO) | BMI Prime |
|---|---|---|
| Below 18.5 | Underweight | below 0.74 |
| 18.5–24.9 | Healthy weight | 0.74–0.99 |
| 25–29.9 | Overweight | 1.00–1.19 |
| 30–34.9 | Obesity class I | 1.20–1.39 |
| 35–39.9 | Obesity class II | 1.40–1.59 |
| 40 and above | Obesity class III | 1.60 and above |
Inputs explained
| Field | What to enter |
|---|---|
| Weight | Units: kg, lb, st, g |
| Height | Units: cm, in, m, ft, mm |
| Target BMI | A number |
| Weekly weight change | Units: kg, lb, st, g |
What each result means
- Current BMI = [Weight]÷([Height]÷100)^2
- Current BMI Prime = [Current BMI]÷25
- Target weight = [Target BMI]×([Height]÷100)^2
- Weight to lose (−) or gain (+) = [Target weight] – [Weight]
- Target BMI Prime = [Target BMI]÷25
- Time at your weekly rate = abs([Weight to lose (−) or gain (+)])÷[Weekly weight change]
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Target weight = target BMI × height²
Change = target weight − current weight
Weeks = |change| ÷ weekly rate
Worked example
Inputs — Weight: 95 kg; Height: 178 cm; Target BMI: 24.9; Weekly weight change: 0.5 kg.
Results — Current BMI = 30; Current BMI Prime = 1.2; Target weight = 78.9 kg; Weight to lose (−) or gain (+) = -16.1 kg; Target BMI Prime = 1; Time at your weekly rate = 32 weeks.
Key terms
- Target BMI
- The BMI you are aiming for.
Frequently asked questions
What BMI should I aim for?
Anywhere from 18.5 to 24.9 is in the healthy range; many people choose the upper end first.
How fast should I lose weight?
About 0.5–1 kg (1–2 lb) a week for most adults.
Does losing weight lower health risk even if I stay overweight?
Yes – 5–10% weight loss has clear benefits.