Ideal Weight Calculator - Broca, Devine & Robinson Formulas

Forget the scale - check three formulas first

There is no single "ideal weight." Three widely used clinical formulas - Broca, Devine and Robinson - each approach the question differently. This calculator runs all three, averages the results, then adjusts for your body frame (small, medium or athletic) and age (over 50 gets a 5% bump). The output is a range, not a single number, because healthy weight spans roughly 10% above and below the midpoint.

How to find your ideal weight - step by step

Height - enter your height in centimeters, measured barefoot against a wall.
Sex - select female or male. Each formula uses different coefficients.
Age - your age in years. The calculator adds a 5% adjustment after age 50 because lean mass shifts with aging.
Body frame - pick small, medium or athletic. Small reduces the average by 5%, athletic increases it by 10%. To estimate your frame, measure your wrist: under 16 cm (men) or 14 cm (women) suggests small.
Read the results - you get the ideal range (min-max), the optimal midpoint, and individual results from Broca, Devine and Robinson.

The three formulas compared

Formula	Male	Female	Origin
Broca	(height - 100) x 0.9	(height - 100) x 0.85	1871, France
Devine	50 + 2.3 x (inches over 60)	45.5 + 2.3 x (inches over 60)	1974, USA
Robinson	52 + 1.9 x (inches over 60)	49 + 1.7 x (inches over 60)	1983, USA

All three formulas use height as the primary variable. Devine and Robinson convert centimeters to inches internally (1 inch = 2.54 cm) and measure from a baseline of 5 feet (60 inches = 152.4 cm).

Ideal weight by height - quick reference

Height	Male (medium frame)	Female (medium frame)
155 cm	51.9 kg	48.4 kg
160 cm	56.2 kg	52.5 kg
165 cm	60.4 kg	56.5 kg
170 cm	64.7 kg	60.6 kg
175 cm	69.0 kg	64.6 kg
180 cm	73.2 kg	68.7 kg
185 cm	77.5 kg	72.7 kg
190 cm	81.7 kg	76.7 kg

Practical examples

Example 1: Male, 175 cm, 30 years, medium frame. Broca: 67.5 kg, Devine: 70.5 kg, Robinson: 68.9 kg. Average: 69.0 kg. Range: 62.1 - 75.9 kg.

Example 2: Female, 165 cm, 25 years, small frame. Broca: 55.3 kg, Devine: 56.9 kg, Robinson: 57.4 kg. Average (small frame -5%): 53.7 kg. Range: 48.3 - 59.1 kg.

Example 3: Male, 190 cm, 28 years, athletic frame. Broca: 81.0 kg, Devine: 84.0 kg, Robinson: 80.1 kg. Average (athletic +10%): 89.9 kg. Range: 80.9 - 98.9 kg.

Example 4: Female, 155 cm, 55 years, medium frame. Broca: 46.8 kg, Devine: 47.9 kg, Robinson: 50.7 kg. Average (age 50+ adjustment +5%): 50.9 kg. Range: 45.8 - 56.0 kg.

Example 5: Male, 180 cm, 40 years, medium frame. Broca: 72.0 kg, Devine: 75.0 kg, Robinson: 72.6 kg. Average: 73.2 kg. Range: 65.9 - 80.5 kg.

FAQ - Frequently asked questions

Which formula is the most accurate?

No single formula is universally best. Broca is simplest and works well for heights near 170 cm. Devine is standard in clinical pharmacology (drug dosing). Robinson is a refinement of Devine with slightly different slopes. Averaging all three gives the most balanced estimate.

Why does the calculator give a range instead of one number?

Healthy weight is not a single point. Two people at the same height can have different bone density, muscle mass and fat distribution. The range spans 10% below to 10% above the calculated midpoint, covering the realistic spread of healthy bodies.

How does body frame affect the result?

A small frame reduces the average by 5% - smaller bones and less muscle carry less weight. An athletic frame adds 10% - wider shoulders, denser bones and more muscle. Medium frame applies no adjustment. Wrist circumference is the easiest way to estimate your frame.

Why is there an age adjustment after 50?

After age 50, body composition shifts: muscle mass decreases while fat mass tends to increase. A slightly higher weight (the 5% adjustment) is associated with better outcomes in older adults - research shows BMI 23 - 27 correlates with lowest mortality in the over-65 population.

Do these formulas work for very tall or very short people?

All three formulas were developed using populations in the 155 - 190 cm range. At extremes (below 150 cm or above 200 cm), accuracy decreases. For people outside this range, BMI-based weight ranges are a better reference.

Is ideal weight the same as healthy weight?

"Ideal weight" from these formulas is a statistical estimate, not a medical diagnosis. Healthy weight depends on many factors: body fat percentage, waist circumference, blood pressure, blood sugar and cholesterol. A person slightly outside the "ideal" range can be perfectly healthy. Use these numbers as a reference point, not a target.

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