About HeightCompare

What this site is

HeightCompare is a set of free tools for comparing and converting height. The centrepiece is a visual comparison board: you add subjects, enter heights in centimetres or feet and inches, and each one is drawn to exact proportion against a shared ruler.

Around it sit the calculators people usually need next - a difference calculator, a unit converter, a full conversion chart, country average data, a percentile estimate, a child height estimate and a BMI calculator. All of it is free, none of it requires an account, and all of it runs in your browser.

Where the data comes from

Different parts of the site have different evidentiary standards, and we try to say which is which:

• Unit conversions are exact arithmetic. One inch is defined as exactly 2.54 cm and one foot as exactly 30.48 cm, by the 1959 international yard and pound agreement. There is no uncertainty in this part of the site at all.
• Country average heights come from NCD Risk Factor Collaboration (NCD-RisC) data, which pools population-based studies and models national means. These are modelled estimates, they are rounded, and small differences between countries should be treated as noise.
• Celebrity and athlete heights are the commonly cited public figures, which usually originate from agency cards, league listings or press material. They frequently include footwear and are often rounded. Every entry carries a note saying so, and every value is editable.
• Animal, dinosaur and landmark heights are the mid-range of published estimates, with the basis stated in the table. Dinosaur figures in particular vary substantially between reconstructions.
• Character heights come from community-maintained profiles rather than official sources in most cases. They are useful for keeping a scale sheet consistent, not as canon measurements.

What we do not claim

This site is not a medical tool. The percentile, child height and BMI calculators are statistical models for general interest. They are not diagnostic, they cannot assess an individual, and they should never be used in place of a clinician's assessment. If you have a concern about your own height or a child's growth, talk to a doctor - a population average cannot answer a personal question.

How the comparison engine works

It is deliberately simple, because simple is verifiable. The tallest subject on the board is mapped to the available drawing height, and every other subject is scaled by the ratio of its own height to that maximum. The ruler is generated from the same scale factor, so the ticks and the figures can never disagree. Because every subject is anchored to one shared baseline, a 20 cm difference always renders as a 20 cm difference.

Nothing is sent anywhere. There is no server-side processing of your comparisons, no account, and no analytics on the values you enter. Exports are rendered in your browser. Share links encode the entire lineup into the URL itself, which is why they work without any stored state on our side.

Accessibility and performance

The site is built as static HTML with no framework, no external font requests and no render-blocking JavaScript. It supports keyboard navigation throughout, including arrow-key reordering of the board, and offers both light and dark themes plus reduced-motion support. If you hit a problem with either, please tell us.

Corrections

We would rather be corrected than be wrong. If you find a figure that does not match its source, a conversion error, or a page that misstates something, use the contact page and include the page and the value. Corrections that can be verified against a primary source are made promptly.