About
About Size It Up
A free size guessing game. One object is drawn at its true size, a second is drawn at a size you have to judge, and the score tells you how close your sense of scale was.
Where the numbers come from
Every object carries a measured dimension in metres, a note on which variant was measured, and a source. There are 206 objects in the library and 206 of them name a source. Where a figure is contested the range is given in the object's own record rather than averaged into a single number.
Why the drawing can be trusted
A round is only fair if both shapes are drawn at one shared scale: one pixel is the same number of metres for the reference and for your guess. The shape you resize is fixed to the object's real measurement along the axis being guessed, and the outline keeps the object's own proportions; the other axis is corrected towards reality by at most 1.6×, and never distorted to hide a bad drawing.
What the site stores
Progress, streaks, preferences and records stay in your browser's local storage. There is no account. The only third-party request is Google Analytics (GA4), which counts visits. Clearing your browser data clears your history with it.
Challenges
A challenge link carries the whole puzzle in the URL itself, so there is no server holding your run and nothing to expire. That also means challenge pages are deliberately kept out of search results — they are for the person you sent the link to.
Something wrong?
If a measurement is off, a silhouette does not read as the thing it names, or a round felt unfair, that is worth fixing. Write to hello@sizeitup.cloud with the object name and what you expected, and it goes on the list. Corrections to a figure are always welcome when they come with a source.