Daily
Five rounds for each category and date, with the date following your time zone. Finish a set to record your result. Returning tomorrow brings another set; older published dates remain available through Past Games.
Play today’s fiveSizekin Game
PAST GAMES · TUESDAY, OCTOBER 27, 2026 · DOESN’T COUNT TOWARD YOUR STREAK
←Oct 27→
Past GamesNo. 3Oct 27
ROUND1 / 5
0 / 1,000
Preparing your round…
Give your intuition a ruler.
Recognising an object and judging its size are different skills. Sizekin puts a measured reference beside a silhouette you control. Adjust the target, submit your estimate, and use the reveal to see where your sense of scale needs a second look.
Two selected animals, measured in the same direction.
Begin with one size you can trust
Our example starts with an emperor penguin recorded at 1.2 metres tall. The selected male red kangaroo is 1.6 metres tall: one penguin's height plus another third. The comparison gives you something more useful than an isolated number—a reference you can picture.
These are the values selected for the entries, not identical measurements for every member of either species. In a real round, check the name, qualifier and measurement label before making the silhouettes look right together.
Three decisions in every round
01 · FIND THE REFERENCE
Read the dark silhouette's marked measurement. Decide whether the question concerns length, height, width, diameter or wingspan. The target is judged against that dimension, not against the area it fills on your screen.
02 · SET A PROPORTION
Start with a rough multiple: shorter than the reference, about equal, or several times larger. Drag or use the ruler to refine it. On touchscreens you can pinch to adjust the target; use the separate zoom controls when you need more room to see.
03 · CHECK YOUR ESTIMATE
Lock in when you are ready to commit. The reveal compares your estimate with the stored measurement and shows the resulting score. Take a moment to identify whether the miss came from the scale, the unit or the endpoints you imagined.
An answer you can compare with your guess
The score measures multiplicative error. Guessing twice the recorded size and guessing half of it receive the same base points. Each Daily round has a weight, so the five base scores combine into a total out of 1,000.
When a run is complete, you can save its result image or create a share link. A challenge link gives a friend the same questions. Choose what to share after checking the preview; a revealed round can include the answer.
Pick the kind of practice you want
all free · no accountRead the measurement guide before trying a different category.
Unlimited
Choose 5, 10, 20 or an endless run. Practise a selected category without replacing your Daily progress. Recent objects are avoided when the category has enough alternatives; an endless run can finish after five rounds.
Play unlimited
Geography
Compare countries by their marked span. Check the direction and included territory before adjusting the outline.
Play geographyKeep a few useful comparisons
See every day’s answersThe examples below use selected library entries. Their bars compare one linear measurement at a time. They are reference notes for learning, not predictions of which pairs will appear in today's puzzle.
Red kangaroo / emperor penguin
1.33× the height
Smart Fortwo / bicycle
1.54× the length
Golf ball / table tennis ball
1.07× the diameter
Build a collection of reference points
A useful reference is something you can picture and describe precisely. Instead of memorising many unrelated numbers, connect one new object to one you already know. The comparison remains useful even when the next question uses a different unit.
When an answer surprises you, check the wording before changing your intuition. Height and length are not interchangeable, and a specific model, specimen or product size can differ from the generic object you had in mind.
The library keeps measurement notes and source credits with each entry. It also distinguishes objects available for new games from retired entries retained for older results. You can inspect that context and send a correction through the feedback page.
Before your next round
- What am I estimating?
- The target's marked linear dimension relative to a measured reference. You resize a silhouette rather than type an answer. Read its label to distinguish height, length, width, diameter and wingspan.
- How is a Daily set chosen?
- Each available category and date has five fixed rounds. Players on that same category and date receive the same set. Your local time zone determines the current date; older dates can be replayed separately.
- Does a small guess score better than a large one?
- Neither direction has an advantage. The score uses the ratio between your guess and the recorded measurement. A 2× guess and a 0.5× guess both earn 45 base points before the round weight is applied.
- Where is my progress saved?
- Browser storage remembers your anonymous player identity and local preferences; submitted rounds are also saved by the server. Clearing site data can break that connection. Progress does not automatically follow you to another device.
- Can I practise a single theme?
- Yes. Choose a category and switch to Unlimited for a new practice run. Its progress is separate from Daily. You can choose a fixed run length or continue in endless mode.
- Can I inspect a measurement?
- Open the library or credits to read the entry's selected measurement, source and artwork attribution. Some measurements are estimates or version-specific; the notes explain the scope recorded for that object.