size it up.

A little perspective

Trust your eye.

Five comparisons. Two objects each time. How close can you get?

  1. Compare

    The object on the left is your measuring stick. Keep resizing — the view automatically zooms out when you need more room. You can also zoom the canvas; both objects scale together without changing your estimate.

  2. Find the right size

    Drag the blue handle, scroll while hovering it, tap − / +, or use the arrow keys. Match the dimension in the question.

  3. Lock it in

    Reveal the real size and earn up to 100 points. Five rounds add up to a maximum of 500.

The first answer in each round counts. A new challenge arrives every day at 00:00 UTC. Object sizes use the specific examples shown in the answer.

Read the full rules and scoring guideLet’s play

A little more perspective

About Size It Up

Big things. Small things. A daily chance to see how they measure up.

Size It Up is a free game about the scale of real-world objects. Compare animals, buildings, spacecraft, sports equipment, and everyday objects by adjusting one object’s size next to another.

Play today’s game

Five rounds, once a day

Each daily Classic or Geography challenge contains five comparisons using ten different objects or countries. There is no timer. Adjust your estimate, lock it in, then discover the actual size and the story behind it.

Each round is worth up to 100 points, for a total of 500. Your score depends on how close your estimated ratio is to the real ratio. A score of 80 does not mean your size estimate was 80% accurate.

A new daily challenge begins at 00:00 UTC, and your first locked answer counts. Earlier daily leaderboards remain available. You can replay past challenges for practice; practice scores do not count toward leaderboards or today’s progress.

Where the dimensions come from

The game’s dimensions come from manufacturer specifications, museums and scientific organizations, landmark operators, and sporting rules. Each revealed answer includes a size explanation and a source link; you can find these again in the round review after finishing.

Real objects are not all identical. A measurement may be a standard size, a representative example, or an explicitly stated maximum. The answer’s label and explanation tell you which comparison the game uses.

Length and height also depend on what is being measured. A basketball hoop is measured to the rim, for example, while a football goal’s width is measured between the inside edges of its posts.

Illustrations, not engineering drawings

The artwork makes size comparisons easier to explore. It is stylized, includes AI-generated illustrations, and may simplify shape or detail. Use the marked measurement and the revealed dimensions to understand the answer, rather than treating an illustration as a technical drawing.

Zooming the view scales both objects together. It changes how much of the comparison you can see, without changing your estimate.

Play and rank automatically.

You can play, share your result and join the leaderboard without signing in. A nickname and avatar are created for this browser. Finishing the daily challenge automatically publishes your score on the leaderboard. Linking a Google or verified email account is optional and lets you recover your progress on another browser or device.

You can edit your nickname, generated avatar, and country or region in your profile without signing in. The Privacy page explains the profile details shown when you complete a daily challenge.

Contact

For feedback, a question about a dimension or source, or a question about your data, email service@sizeitup.xyz.

If a comparison looks wrong, include the challenge’s UTC date and the objects involved so the example can be identified.

The Contact page lists useful details for game feedback and questions about your data.