Reverse BMI Calculator
Set a target BMI, get the exact weight you need to reach it — in kilograms, pounds, or stones. The fastest way to turn a BMI goal into a real, trackable weight.
Category: Normal weight
Quick targets
How the reverse BMI calculator works
Choose your units and enter your height
Toggle between metric (cm) and imperial (ft / in). Enter your real height — even a 2 cm error noticeably shifts the result because BMI uses height squared.
Set a target BMI on the slider
Drag the slider, or tap one of the Quick Targets — bottom of healthy range (18.5), lowest-mortality (22), top of healthy range (24.9), or the overweight / obese thresholds.
Read your target weight in kg, lbs and stones
The calculator returns the exact weight that produces your chosen BMI at your height, plus the full healthy weight range for context. Use this number as your weight-loss or weight-gain goal.
The reverse BMI formula
The standard BMI formula is BMI = weight (kg) ÷ height (m)². To reverse it, you rearrange for weight:
Target weight (kg) = Target BMI × Height (m)²
Worked example for a 1.70 m adult aiming for a BMI of 22: 22 × 1.70 × 1.70 = 63.6 kg (140.1 lbs · 10 st 0.1 lb). That is the weight that would produce a BMI of exactly 22 at this height.
Reverse BMI — Common Questions
Quick answers to the most common questions
A reverse BMI calculator works backwards from the standard BMI formula. Instead of taking your weight and height to give you a BMI score, you set a target BMI and a height, and it tells you the exact weight that would produce that BMI. It is the easiest way to turn a healthy-BMI goal into a real, trackable weight in kilograms, pounds, or stones.
The standard BMI formula is BMI = weight (kg) ÷ height (m)². To reverse it, multiply your target BMI by your height in metres squared. So for a target BMI of 22 at 1.70 m: 22 × 1.70 × 1.70 = 63.6 kg. Our calculator does this instantly and also converts the result into pounds and UK stones.
For most healthy adults the WHO and NHS define the healthy BMI range as 18.5 to 24.9. Population studies show that a BMI between 20 and 22.5 has the lowest all-cause mortality risk, which is why 22 is a common evidence-based target. If you are over 65 a slightly higher range of 23 to 27 may be more appropriate — speak to your GP.
Subtract your target weight (calculated by this tool) from your current weight. For example, if you currently weigh 90 kg and the calculator says BMI 24 at your height equals 75 kg, you need to lose 15 kg. A safe rate of weight loss is 0.5 to 1 kg per week through a 500-calorie daily deficit, so 15 kg typically takes 15 to 30 weeks.
Yes. If your BMI is below 18.5 you can use the calculator to find the weight that would move you into the healthy range. Aim for 0.25 to 0.5 kg of healthy weight gain per week through a small calorie surplus, protein intake of 1.6 to 2.0 g per kg, and resistance training to build lean mass rather than just fat.
BMI does not distinguish between muscle and fat, so reverse BMI gives you a weight that produces a specific BMI — not necessarily an ideal body composition. If you do regular resistance training, a target BMI of 25 or even slightly above can still be healthy. Pair the result with a body fat measurement and waist circumference for a fuller picture.
Target weight (from this calculator) is the weight that produces a specific BMI at your height. Ideal weight (from clinical formulas like Devine or Robinson) is an estimated weight based on height and gender alone, used historically for medication dosing. Target BMI is the simpler, more flexible goal — you choose where in the healthy range you want to be.
Yes. The result is shown in three units side by side: kilograms (metric), pounds (imperial), and stones-and-pounds (UK). For example, 70 kg = 154.3 lbs = 11 st 0.3 lb. You can also enter your height in either centimetres or feet and inches via the unit toggle.
Have another question? Browse our full article library or try a free calculator.
Use these alongside your reverse BMI result
BMI Calculator
Start hereCheck your current BMI to see how far you are from your target.
Open calculatorCalorie Calculator
Find the daily calorie deficit you need to reach your target weight.
Open calculatorIdeal Weight Calculator
Cross-check your target against four clinical formulas.
Open calculatorBody Fat Calculator
Make sure your target is realistic for your body composition.
Open calculator