A little perspective
How to play Size It Up
Compare two objects. Trust your eye. Find out how close you are to their real proportions.
- rounds each day
- 5
- possible points
- 500
- new daily challenge
- 00:00 UTC
Three steps to your first guess
Compare
Read the question to see whether you are comparing length or height. Use the object on the left as your reference and picture the real size of the object on the right.
Resize
Drag the blue handle to resize the object on the right. You can also scroll over the handle, use the plus and minus buttons, or focus the handle and press the arrow keys.
Lock in
When the proportions look right, lock in your estimate. You will see the actual size, your points and a source for the measurement. Your first locked answer is final; continue through all five rounds to see your total.
See it in action
A 44-second introduction in English, using a T. rex and other real-world objects.
Watch the Size It Up introduction on YouTubeKeep the right perspective
The grid helps you judge proportions; a square does not represent a fixed number of metres. If an object reaches the edge, the view automatically zooms out to keep the comparison visible. Zooming the view scales both objects together and does not change your answer.
Compare the dimension named in the question. Classic rounds use the stated length or height, not the area of the illustration. Measurements refer to the particular example, standard dimension or recorded maximum explained in the answer.
In Geography, north is up. Compare the countries’ east–west width or north–south height, not their land area. Simplified outlines use approximate spans; some remote islands are omitted, and each answer explains the territory included.
How scoring works
Each round awards up to 100 points, for a maximum of 500 across five rounds. The closer your estimated size ratio is to the actual ratio, the higher your score. Guessing twice the true size and guessing half the true size earn the same points.
| Your estimate | Points out of 100 |
|---|---|
| Exactly the actual size | 100 |
| 6% larger than the actual size | 92 |
| Twice the actual size | 35 |
| Half the actual size | 35 |
Points are rounded to the nearest whole number. Your score is not an accuracy percentage: 92 points does not mean your size estimate was 92% accurate.
See the scoring formula
Let g be your estimated ratio and a the actual ratio. ln is the natural logarithm; the vertical bars take the absolute value, and round gives the nearest whole number. Both ratios must be positive.
round(100 × exp(−1.5 × |ln(g / a)|))
A fresh challenge, every day
Classic and Geography each have five rounds per day, with no timer. A new challenge begins at 00:00 UTC. These modes have separate daily progress and leaderboards, so you can play both each day.
The daily leaderboard ranks submitted scores from that day. Monthly and all-time boards rank the average of your submitted daily scores and also show total points. Only submitted days count; equal scores or averages share a rank. Finish all five rounds and your score automatically joins the leaderboard with your current nickname, without signing in. You can edit your nickname, avatar, and country or region in your profile. Your email is never public. Link this browser’s progress to an account so you can return after clearing browser data or switching devices.