The game behind the numbers
What is SizeDex?
SizeDex is an independent daily Pokémon size-comparison game built around a simple idea: reading a Pokédex height is easy, but actually picturing the difference between two Pokémon is much harder. Each round gives you one correctly scaled reference Pokémon and one target Pokémon. Resize the target until the relationship looks right, lock your estimate, and see how close your visual judgment was to the listed height ratio.
The ranked Daily Challenge contains 10 comparisons shared by players for the same UTC date. After finishing it, you can continue with unlimited random practice games. The leaderboard is optional, and the main game can be played without creating an account.
How a round is scored
SizeDex uses proportional accuracy rather than raw meter error. Your estimated height and the target’s listed height are compared by dividing the smaller value by the larger one and converting the result to a percentage. An exact visual match earns 100%. If your estimate is twice the real height—or half of it—the round earns 50%. The final score is the average of all 10 rounds, rounded to one decimal place.
This approach lets tiny and enormous Pokémon use the same scoring logic without unfairly punishing large species simply because their measurements involve bigger numbers.
Where the size data comes from
The current browser game loads standard Pokémon and form records from PokéAPI and converts the supplied height values into meters. Artwork is selected from sprite and artwork resources available through the API. Special forms can require additional handling: supported Gigantamax forms, for example, use explicit minimum-height values and are marked with a plus sign where appropriate.
Individual entries can be reviewed against additional references when a form or measurement needs clarification. SizeDex is designed as a game built from published size data, not as an official Pokédex.
Daily Challenge vs. practice
The Daily Challenge uses a deterministic seed, so players receive the same 10-pair set for that UTC date. That shared set is what makes daily scores comparable. The round generator mixes mostly readable size relationships with a few wider wildcard comparisons so a run has both approachable and surprising moments.
Practice mode creates new random 10-round games and is intentionally unranked. It is there for learning, experimenting with scale, and continuing to play after the daily result is complete.
Leaderboard, progress and privacy
The public leaderboard is optional. Players who submit a Daily Challenge score choose a username and verify an email address through passwordless authentication. Email addresses are not shown publicly. Backend validation requires an authenticated verified user, checks the date and score range, and limits repeated submissions.
Daily progress, streaks, theme preference, and some cached game data are stored locally in the browser. More detail about authentication, analytics, advertising, local storage, and data handling is available in the Privacy Policy.