Methodology

How we measure sizes

Where the sizes on this website come from, what exactly each one measures, how we round and convert them, and what happens when we get one wrong.

Where the numbers come from

Every item on this website — a thing, its size, what exactly that size measures and a short fact about it — was drafted with the help of an AI model, which had to name the source the item is based on: for example a manufacturer's specifications or a museum's description.

We don't put a size on this website without a source. A size page names its sources and links to the pages its size was checked against.

How every item is checked

Drafted with AI from a cited source. A model writes the item's size, what it measures and a fact, and names its source. The silhouette is generated as an image with AI and traced into a vector shape.
Checked automatically. A second, separate AI pass reviews each item's size and fact and flags anything doubtful. Flagged items never appear on this website.
Verified against its sources, page by page. An AI agent opens the actual source pages, confirms the size and what exactly it measures, and adds the links to the item's size page. A page that has been through this shows a “Last reviewed” date; a page without one rests on the two checks above. When sources disagree with a size, we correct it or take the page down.
Spot-checked by the team. People on our team check samples of this work by hand.
Corrected when you find a mistake. Reports from readers and players are checked against the sources, and every outcome is logged below.

We want to be plain about this: the checks in steps 2 and 3 are done by AI, not by a person reading every item. That is why size pages link their sources, so you can check them yourself, and why we keep a public log of corrections.

Articles are handled differently: when an article is drafted with AI, a person reads it and checks every claim it flags before it is published.

What exactly is measured

A size only means something if you know what it measures, so the words under each size say exactly that. These are the terms we use:

Term	What it means
Height	From the ground or the base to the highest point.
Shoulder height	For animals on four legs: from the ground to the top of the shoulders. It is the usual way to measure them, because the head moves.
Standing height	A person or animal standing upright, from the ground to the top of the head.
Elevation	How high a summit is above sea level.
Vertical drop	How far a waterfall or a cliff falls, from top to bottom.
Length	From one end to the other along the longest side: vehicles, ships, objects.
Body length	From the tip of the nose to the base of the tail, without the tail.
Total length	From the tip of the nose to the tip of the tail.
Wingspan	From one wing tip to the other, with the wings spread.
Leg span	From the tip of one leg to the tip of the opposite leg, legs spread, as for spiders and crabs.
Width	From one side to the other.
Diameter	Straight across a round thing, through its middle: cells, grains, planets.

An animal and a building

“How tall” depends on what you measure. For an animal on four legs, the usual measure is shoulder height; for one that stands upright, the height to the top of its head. For a building or a tower, it is the height of the structure from the ground to its top, counting a spire that is part of the design but not an antenna added on top. Where a source measures another way, the words under the size say so.

Which individual

Animals and plants vary in size, so each size also says which individual it describes: a typical adult, a mature specimen, or the largest reliably recorded one — which, for many fossil species, is the only one ever measured.

Rounding and units

Every size is shown in both unit systems, metric first, with imperial in brackets: 1.7 m (5 ft 7 in). The website can't know where you are, so it always shows both, rounded the same way the game rounds them.

Precision. Values of 100 or more are whole numbers, values from 10 to 100 have one decimal place, and smaller values have up to two. Trailing zeros are dropped: 330 m, 23.8 m, 7.5 µm.
Metric units. Each size uses the largest unit in which it is at least 1 after rounding, from kilometres down to nanometres, so half a millimetre reads 500 µm. Heights stay in metres up to 10 km, the way mountains are usually quoted: 8,849 m.
Imperial units. Below a foot, sizes are in inches with decimals (5.91 in); from 1 to 10 feet, in feet and whole inches (5 ft 7 in); from 10 feet, in whole feet (1,083 ft); from a mile, in miles (heights from 10 miles). Below 0.1 inch (2.54 mm), imperial units aren't used and the size is shown in metric only.
Exact conversions. 1 inch is exactly 2.54 cm, 1 foot is 30.48 cm and 1 mile is 1.609344 km, and we convert with those definitions.
Ratios. When two sizes are compared, the ratio is rounded to two significant figures, for example 12× or 1.5×.
Rounding is only for display. Comparisons and scores use the unrounded values. In the game, every answer is judged by the ratio between sizes, so a round scores the same in metric and in imperial.

Corrections

If you think a size is wrong, please tell us. Use the contact form and choose “A correction to a size”; the “Report a mistake” link on every size page fills in the item for you. It helps to say what you think is wrong and where you found a different number.

We check each report against the sources. If the size needs to change, we correct it and the page updates. A size page's “Last reviewed” date shows when its size was last checked against its sources; it changes only when we check it again, never for cosmetic edits.

Every resolved report, whether or not we changed the size, goes into the correction log below with a short note from us. The log never shows who sent a report: no names, no email addresses, no messages.

Correction log

No corrections yet. When we resolve a report, it will appear here.