Last updated: June 2026
Reverse BMI Calculator: Find the Weight You Need to Hit a Target BMI
A standard BMI calculator tells you your current BMI given your height and weight. A reverse BMI calculator does the opposite — you input your height and a target BMI, and it outputs the weight you would need to reach to hit that number. It turns a vague goal (“I want to lose weight”) into a specific one (“I need to get to 172 lb”).
Calculate Your Current BMI First
Find your current BMI, then use the formula below to calculate the weight you need to reach your target category.
The Reverse BMI Formula
Standard BMI is calculated as:
BMI = weight (kg) ÷ height (m)²
Rearranging to solve for weight gives the reverse BMI formula:
Target weight (kg) = Target BMI × height (m)²
To convert height from feet and inches to metres: multiply total inches by 0.0254.
Step-by-step example
Person: 5’8″ (68 inches = 1.727 m), current BMI 31, wants to reach BMI 24.9.
- Convert height: 68 × 0.0254 = 1.727 m
- Square the height: 1.727² = 2.982
- Multiply by target BMI: 24.9 × 2.982 = 74.3 kg (164 lb)
That person currently weighs roughly 203 lb (BMI 31 × 2.982 = 92.2 kg = ~203 lb). They need to lose approximately 39 lb to cross into the healthy BMI range.
Related Reading
How to Lower Your BMI: 6 Evidence-Based Strategies That Work →
Quick Reference: Target Weights by Height and BMI
The table below shows target weights for three common BMI goals across a range of heights. All values in pounds, rounded to the nearest pound.
| Height | Weight at BMI 24.9 (top of healthy range) |
Weight at BMI 29.9 (top of overweight range) |
Weight at BMI 18.5 (bottom of healthy range) |
|---|---|---|---|
| 5′ 0″ | 128 lb | 153 lb | 95 lb |
| 5′ 2″ | 136 lb | 163 lb | 101 lb |
| 5′ 4″ | 145 lb | 174 lb | 108 lb |
| 5′ 6″ | 154 lb | 185 lb | 115 lb |
| 5′ 8″ | 164 lb | 197 lb | 122 lb |
| 5′ 10″ | 174 lb | 209 lb | 129 lb |
| 6′ 0″ | 184 lb | 221 lb | 137 lb |
| 6′ 2″ | 194 lb | 233 lb | 144 lb |
BMI Categories — Choosing Your Target
When using a reverse BMI calculator, you first need to decide what BMI to target. The standard adult categories are:
| Category | BMI Range | Common target |
|---|---|---|
| Underweight | Below 18.5 | Not a health goal for most adults |
| Healthy weight | 18.5 – 24.9 | Most common target — aim for 22–24 |
| Overweight | 25.0 – 29.9 | Interim target if healthy range is a long way off |
| Class I Obesity | 30.0 – 34.9 | BMI 30 is the threshold for medication eligibility in many guidelines |
| Class II Obesity | 35.0 – 39.9 | BMI 35 = surgery eligibility with a comorbidity |
| Class III Obesity | 40.0 + | BMI 40 = surgery eligibility without a comorbidity |
For most people without specific medical thresholds to meet, targeting BMI 22–24 places you comfortably in the healthy range with a buffer above 18.5. If you are aiming for a clinical threshold (surgery eligibility, insurance, military standards), use the exact cutoff your situation requires.
Why Would You Use a Reverse BMI Calculator?
Weight loss goal-setting
Knowing you want to “lose 30 pounds” is motivating but arbitrary. Knowing you want to drop from BMI 31 to BMI 24.9 — and that this requires losing exactly 37 lb for your height — is actionable. It breaks a vague ambition into a defined finish line.
Bariatric surgery eligibility
Bariatric surgery is generally available to adults with BMI ≥ 40, or BMI ≥ 35 with an obesity-related comorbidity. Some programmes require candidates to reduce BMI before surgery to reduce operative risk. A reverse BMI calculation tells a candidate the weight ceiling they need to stay below — or the weight they need to get above a minimum threshold to remain eligible.
Military, insurance, and sports standards
Many military branches, life insurance policies, and athletic programmes use BMI cutoffs. The US Army, for example, uses BMI screening with upper limits that vary by age and sex. A reverse BMI calculation gives the precise weight limit for any specific BMI requirement.
Athlete planning
Combat sport athletes cutting to a specific weight class sometimes use reverse BMI as one reference point. Note that BMI is particularly imprecise for lean, muscular athletes — a separate body fat percentage assessment is more meaningful in that context.
Limitations of the Reverse BMI Approach
The reverse BMI calculation inherits all the limitations of BMI itself. Because BMI uses only height and weight, it cannot distinguish between fat and muscle. A 5’10” person who weighs 174 lb with a BMI of 25.0 could be either overfat or a lean, muscular athlete — the number alone does not tell you which.
Practically, this means the target weight you calculate using reverse BMI is a reference point, not a health verdict. For most sedentary and lightly active adults, landing in the healthy BMI range reliably correlates with lower health risk. For athletes, the target weight may need adjusting upward to avoid losing muscle alongside fat.
If you want a target that accounts for body composition rather than just weight, pair reverse BMI with a target body fat percentage — for example, targeting BMI 24.9 at under 20% body fat for a man, or under 28% for a woman.
How Much Weight Loss Per Week Gets You There?
Once you know your target weight from the reverse BMI formula, you can estimate a timeline.
| Weekly weight loss rate | Approximate calorie deficit required | Weeks to lose 30 lb |
|---|---|---|
| 0.5 lb / week | ~250 kcal/day | 60 weeks (~14 months) |
| 1 lb / week | ~500 kcal/day | 30 weeks (~7 months) |
| 1.5 lb / week | ~750 kcal/day | 20 weeks (~5 months) |
Most evidence supports 0.5–1 lb per week as a sustainable rate that minimises muscle loss. Faster rates are possible with medical supervision or medication, but the body adapts to larger deficits over time, slowing progress.
Start With Your Current BMI
Calculate your starting BMI, then apply the reverse formula above to find your target weight.
