Height Calculator

What This Tool Does

This calculator does two things: it estimates a child’s likely adult height range based on both parents’ heights, and it converts height between centimeters and feet/inches.

You can also use this Post Office FD calculator.

How It’s Calculated

Height prediction uses the mid-parental height method, a standard clinical approach established by researcher J.M. Tanner in 1970 and still widely used today.

For boys: (Father’s height + Mother’s height + 13 cm) ÷ 2 For girls: (Father’s height + Mother’s height − 13 cm) ÷ 2

Worked example: Father is 178 cm, mother is 163 cm.

• For a boy: (178 + 163 + 13) ÷ 2 = 354 ÷ 2 = 183.5 cm (about 6’0″)
• For a girl, same parents: (178 + 163 − 13) ÷ 2 = 328 ÷ 2 = 164 cm (about 5’4.5″)

This isn’t a single precise number — it’s a midpoint estimate, typically with a realistic range of roughly ±8–10 cm (about 3–4 inches) covering the 3rd to 97th percentile of likely outcomes.

Unit conversion is straightforward: 1 inch = 2.54 cm, so converting feet/inches to cm (or back) is a direct multiplication or division.

Edge Cases and Special Rules

• Wide uncertainty range: Even under ideal conditions, this method has a meaningful margin of error — treat the result as a rough midpoint, not a guarantee.
• Self-reported parent heights are often inaccurate: Studies have found people frequently overestimate their own height by a centimeter or more, which shifts the prediction slightly.
• Validated mainly on specific populations: This method, like most simple prediction formulas, was developed and studied primarily on certain population groups, so accuracy can vary for others.
• Not diagnostic: This tool doesn’t account for nutrition, health conditions, or other factors that can meaningfully affect a child’s actual growth.

Other Height Prediction Methods

The mid-parental method is the simplest approach, but not the only one. Bone age assessment (using a hand and wrist X-ray, compared against reference standards) is considered more accurate but requires a medical setting. The Khamis-Roche method improves on simple parental averaging by also factoring in the child’s current height and weight, though it’s most validated for children aged 4–9. Growth charts, like those from public health agencies, track a child’s measurements against population percentiles over time rather than predicting a single future number. Each method trades off simplicity for accuracy differently.

Who Uses This

• Parents curious about a rough estimate of their child’s likely adult height
• Students or researchers learning about growth prediction methods
• Anyone needing a quick, accurate conversion between cm and feet/inches
• Healthcare-adjacent contexts where mid-parental height is used as an initial reference point, not a diagnosis

Height Prediction vs. Height Conversion

These are different kinds of calculations bundled into one tool. Height conversion (cm to feet/inches or back) is exact math — there’s no uncertainty, just a fixed ratio. Height prediction is a statistical estimate based on population patterns, with a real margin of error built in. Don’t treat a predicted height with the same confidence as a converted one.

FAQ

How accurate is child height prediction?

It’s a rough estimate — even the standard method has a realistic margin of error of several centimeters in either direction.

Does nutrition affect a child’s eventual height?

Yes, alongside genetics — nutrition, health, and sleep during childhood can all influence how close a child gets to their genetic potential.

Why do different height prediction methods give different results?

Each method uses different inputs and was validated differently, so results can vary — none of them is a precise guarantee.

Should I be concerned if my child is shorter than the predicted range?

Not necessarily — normal variation is wide. If you have a specific concern about your child’s growth, a pediatrician can assess it properly.

How do I convert height between cm and feet/inches?

Multiply feet by 30.48 and inches by 2.54 to get centimeters, or divide by those figures to convert back.

Try It Above

Enter the details in the calculator above to get a predicted height range or a unit conversion instantly. Predictions are general estimates only — for any real concern about a child’s growth, consult a pediatrician.