Height Comparison Tool

How the height comparison tool works

Add a person and they appear on the chart as a silhouette whose height is their real height, drawn at whatever scale the chart is currently using. Add a second and both are redrawn together, so the two figures stand in exactly the ratio their heights do. Add eighteen more and nothing about that changes: the chart gets wider and scrolls, and nobody is squashed to make room.

Everything you can change is on the left. A name, because a chart of unlabelled figures is a puzzle. A male or female silhouette, which changes the shape and never the height. A height in feet and inches or in centimetres, whichever you happen to think in. A colour, so a particular person is easy to find once there are ten of them. Each person can be edited or removed afterwards, and the chart, the ruler, the summary and the difference all follow immediately.

Nothing is sent anywhere. The whole tool is JavaScript running in your own browser, which is also why it keeps working if you lose your connection after the page has loaded.

How to compare two people's heights

For the commonest case — two people, one question — use Quick compare for a ready-made pair, or add both yourself. With exactly two people on the chart, a panel appears underneath giving the gap between them in both units and naming which of the two is taller. It is worded from the heights rather than from the order you typed them in, so adding the shorter person first does not produce a sentence that reads backwards.

Beyond two people the panel disappears, because "taller than" stops having a single answer. The summary table below the chart carries every person's height in both units instead, which is also the version a screen reader reads out and the version that survives being printed.

Feet and inches to centimetres

The two conversions this page rests on are definitions rather than measurements, so they are exact in both directions. The international inch has been exactly 2.54 cm since 1959, and a foot is twelve of them — exactly 30.48 cm.

cm = feet × 30.48 + inches × 2.54

Going the other way, divide by 2.54 for total inches, take the whole feet out with a division by twelve, and what remains is the inches. The only care needed is at the rounding: 182.5 cm is 5 feet and 11.85 inches, and rounding that to the nearest inch has to produce 6 ft 0 in rather than 5 ft 12 in.

Heights are stored in centimetres whichever way you type them, and converted only when they are shown. That matters more than it sounds: a tool that stored 5 ft 10 in as "5 and 10" and converted on every redraw would accumulate rounding, and somebody who typed 177.8 cm would find it had quietly become 177.8 → 5 ft 10 in → 177.8 → 5 ft 10 in and eventually 178.

What a height difference actually looks like

Most people are poor at picturing a stated gap, which is the whole reason this page draws rather than prints. A few reference points worth carrying around:

• 2.5 cm (1 inch) — hard to see standing apart, obvious standing back to back.
• 5 cm (2 inches) — roughly the difference a pair of thick-soled shoes makes.
• 10 cm (4 inches) — a clear step in a photograph; eye level moves to about eyebrow level.
• 15 cm (just under 6 inches) — the shorter person is looking up in conversation.
• 30 cm (about a foot) — the gap between an average adult and a ten-year-old.

The chart makes those visible rather than described. A 15 cm gap between two adults looks modest; the same 15 cm between a 90 cm toddler and a 105 cm child is a sixth of the whole figure and looks enormous. Both readings are correct, and the difference between them is exactly what a proportional drawing shows and a pair of numbers does not.

How the visual height is calculated

There is one scale on the chart, and it is the only thing that decides how tall anything is drawn.

scale = chart height in pixels ÷ ruler top in cm

figure height in pixels = person's height in cm × scale

The ruler's top is set from the tallest person — rounded up to the next 10 cm, with about 6% of headroom so nobody's head touches the ceiling — and never below 200 cm, so a chart of children still reads as a height chart. Add somebody taller and the ruler rises, the scale falls, and everybody is redrawn together. The picture zooms out; the proportions do not move.

Two details make that claim survive contact with a real browser. The first is that a figure is scaled on both axes by the same number, so a taller person is also proportionally wider — a model stretched vertically to fill a box would be the easy way to do this and would be a lie. The second is that every figure is positioned from its feet rather than its head: the drawing is moved down by the chart height minus its own height, which puts the soles of every figure on the same line to the pixel whatever the height.

Both are asserted in the project's test suite rather than checked by eye, across a sweep of chart sizes and height pairs, because "the figures look about right" is not a test.

What the figures do and do not show

The silhouettes are neutral figures at ordinary artist's proportions — a head about one seven-and-a-half of standing height — with a male and a female shape that differ in the shoulders, the waist and the hips. They are drawn as vector shapes, so they stay sharp at any size and take no time to load.

What they are not is a body. Two people of the same height can have very different leg-to-torso ratios, build and posture, and the chart knows nothing about any of that. The gender choice is a drawing decision and has no effect at all on the height: switch a 170 cm person from one silhouette to the other and the figure is drawn to precisely the same height, which you can confirm against the ruler.

Sharing and saving a comparison

Share builds a link with the whole comparison inside the address — names, heights, genders and colours — so opening it anywhere rebuilds the same chart with no account and no database. Every value is checked again when the link is opened, so a link that has been truncated by a chat app, or edited by hand, loads an empty chart rather than doing anything strange.

Download saves the chart as a PNG: the figures, the names, the heights, the ruler and the floor line on a clean background. It is produced from the same drawing the page is showing, so the proportions in the file are the proportions on screen.

Limitations

This page compares heights you supply. It does not estimate anybody's height from a photograph, predict a child's adult height, or know how tall any particular person is. A comparison is only as good as the two measurements in it, and most self-reported heights are generous by an inch or so — measure without shoes, heels together, standing straight against a wall, if the answer matters.

Heights are also not fixed. Almost everybody is taller in the morning than at night, by up to about 2 cm, as the spinal discs compress through the day. That is larger than plenty of the differences people come here to look at, which is worth knowing before treating a one-centimetre gap as settled.

Frequently asked questions