Ideal Weight Calculator
Compare ideal body weight across the Robinson, Miller, Devine and Hamwi formulas.
About Ideal Weight Calculator
The Devine formula gives a single reference weight based on height and sex, while the BMI-based range shows the span of weights considered healthy for your height (BMI 18.5–24.9).
Formulas
Devine formula — Male
IBW (kg) = 50 + 2.3 × (height in inches − 60)
- 60
- Five feet expressed in inches
- IBW
- Ideal body weight in kilograms
- h_in
- Height in inches
Devine formula — Female
IBW (kg) = 45.5 + 2.3 × (height in inches − 60)
- 60
- Five feet expressed in inches
- IBW
- Ideal body weight in kilograms
- h_in
- Height in inches
Healthy BMI range
Healthy weight range = BMI × height (m)² for BMI 18.5 to 24.9
- W_low
- Lower bound of healthy weight (kg)
- W_high
- Upper bound of healthy weight (kg)
- h_m
- Height in metres
Worked example
With the default values below, Ideal Weight Calculator returns Ideal Weight (Devine) of 70.5. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Sexone of Male, Female
- Male
- Height (cm)accepts 120–230 cm
- 175 cm
Results
- Ideal Weight (Devine)
- 70.5
- Healthy Range — Low (kg)
- 56.7
- Healthy Range — High (kg)
- 76.3
Step by step
- 1Convert height to inches= 68.90 in
- 2Inches over 5 ft (60 in)= 8.90 in
- 3Devine formula — Male: 50 + 2.3 × over5ft= 70.5 kg
- 4Convert height to metres for BMI range= 1.750 m
- 5Healthy weight range (BMI 18.5 – 24.9)= 56.7 – 76.3 kg
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
- This is an estimate and not medical advice. Ideal weight varies with individual body composition, age, and health conditions. Consult a healthcare professional for personalised guidance.
- This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Ideal Weight Calculator — full guide
Two answers, deliberately
Ask what someone "should" weigh and there are two defensible replies: a single reference figure, or a range. This page shows both — the Devine formula for the point estimate and the healthy BMI band for the range — because the two are built on different logic and disagreeing is informative.
The Devine formula
IBW (kg) = 50 + 2.3 × (height in inches − 60) for men
IBW (kg) = 45.5 + 2.3 × (height in inches − 60) for women
Sixty inches is five feet, the formula's baseline. Each inch above it adds 2.3 kg. Height entered in centimetres is divided by 2.54 first, and the inches-over-five-feet term is floored at zero.
The BMI band
Healthy weight = BMI × height (m)², evaluated at BMI 18.5 and 24.9 — the WHO normal-weight boundaries for adults.
Worked example at 175 cm
175 ÷ 2.54 = 68.90inches- Inches over five feet:
68.90 − 60 = 8.90 - Devine, male:
50 + 2.3 × 8.90 = 70.5kg - Devine, female:
45.5 + 2.3 × 8.90 = 66.0kg - Height in metres: 1.75, so
1.75² = 3.0625 - Band:
18.5 × 3.0625 = 56.7kg to24.9 × 3.0625 = 76.3kg
Why the two disagree
Devine is linear in inches; the BMI band is quadratic in metres. That makes Devine sit high for tall people and low for short ones. The 70.5 kg male figure above lands in the upper half of a 56.7–76.3 kg band whose midpoint is 66.5 kg. Run a 162 cm woman and it reverses: Devine gives 54.2 kg against a 48.6–65.3 kg band with a 56.9 kg midpoint, so the point estimate falls below centre.
Using the output
Treat the band as the working target and the Devine number as one landmark inside it. Someone 175 cm and 80 kg is at BMI 26.1, above the band; reaching 76.3 kg brings them to the 24.9 boundary — a 3.7 kg move, not a dramatic one.
Limitations
- Height and sex are the only inputs. Frame size, age, muscle mass and ethnicity-specific BMI cut-offs are not modelled.
- Devine was derived for clinical drug dosing, not aesthetics or athletic performance.
- Below five feet the inches term hits its floor, so the result sticks at 50 kg for men and 45.5 kg for women regardless of height — use the BMI band instead in that range.
- A single number cannot distinguish muscle from fat; this is an estimate, not medical advice.
Cross-check with BMI, measure composition with the body fat calculator, and plan the change with calorie needs.
This is an estimate and not medical advice. Ideal weight varies with individual body composition, age, and health conditions. Consult a healthcare professional for personalised guidance.
Frequently Asked Questions
Which number should I aim for?
Treat the BMI range as your healthy target zone; the Devine figure is one point of reference within it. Individual ideal weight depends on muscle, frame, and health factors.
Is ideal weight one exact number?
No. Healthy weight is a range, and factors like muscle mass and body composition matter more than a single target.
Why does the Devine formula start measuring from five feet?
It was published as a clinical dosing rule with 60 inches as its base: 50 kg for a five-foot man, 45.5 kg for a five-foot woman, plus 2.3 kg an inch above that. Nothing in it was fitted below five feet, which is why this page floors the inches term at zero rather than extrapolating downwards.
The Devine figure sits above the middle of my healthy range — is something wrong?
No, that is the formulas diverging by design. At 175 cm the male Devine result is 70.5 kg against a 56.7–76.3 kg band centred on 66.5 kg. Because Devine grows linearly with height while the band grows with height squared, taller people see the point estimate ride high and shorter people see it sit low.
Does the result account for my build or a lower-limb amputation?
It does not. The page takes only height and sex, so broad-framed and slight-framed people of the same height get the same answer. Clinical practice uses adjustments — frame-size corrections, or subtracting a percentage of ideal weight per missing limb segment — that need a clinician to apply properly.
I am a few kilos above the top of the range — how much does that matter?
Work out the actual gap before reacting. At 175 cm the band tops out at 76.3 kg, so 80 kg is 3.7 kg over and gives BMI 26.1 — inside the overweight band but only just. Weight-range boundaries are statistical lines, not health thresholds that flip at a single kilogram.