About the project
What is SizeDex?
SizeDex is an independent fan-made browser game about one very specific Pokémon question: how good are you at judging their sizes? Instead of asking for trivia from a menu, SizeDex turns listed Pokémon heights into a visual estimation game. You are given one Pokémon as a correctly scaled reference and another Pokémon to resize. Your goal is to make the relationship between the two look as close to the listed height ratio as possible.
Why SizeDex exists
Pokémon sizes are easy to read in a Pokédex entry and surprisingly difficult to picture. A number such as 0.4 m, 1.7 m, or 6.5 m does not always create an intuitive mental image, especially when two very different creatures are compared side by side. SizeDex was built to turn those numbers into something interactive.
The idea is deliberately simple: see a reference, estimate the target, lock in the guess, and immediately compare your estimate with the listed size. That makes the site part game, part visual reference, and part daily challenge. The focus is not on memorizing every number. It is on developing a sense for scale and seeing which Pokémon are much smaller or larger than they appear in artwork, games, or animation.
Daily Challenge and practice mode
The ranked Daily Challenge contains 10 comparisons. Everyone receives the same daily set for that UTC date, which makes scores comparable between players. Once the Daily Challenge is complete, players can continue with unlimited random practice games. Practice games use the same core mechanics but do not affect the ranked daily leaderboard.
Daily results are stored locally in the browser so a player can leave and return without immediately losing progress. The site also keeps basic local statistics such as current streak, best streak, best daily score, and average daily score. These local statistics remain on the device unless browser storage is cleared.
Height data and forms
SizeDex currently loads standard Pokémon and form information from PokéAPI. Heights supplied by the API are converted to meters for the comparison system. Some special forms need additional treatment. For example, Gigantamax forms use large listed minimum heights, so SizeDex maintains explicit values for supported Gigantamax entries and marks them as minimum heights where appropriate.
Pokémon data is not always presented identically across every source, particularly for unusual forms or special mechanics. The game is designed so individual entries can be manually reviewed and corrected when a better source is available. Sources such as Bulbapedia can be used as a cross-check during data review, but PokéAPI is the live source used by the current browser client for the standard dataset.
The leaderboard
The leaderboard is optional. Players who want a public ranking can choose a username and verify an email address through a passwordless sign-in flow. The public leaderboard shows usernames and scores, not email addresses. Only Daily Challenge scores count toward the ranked board, and only the best score associated with a player for the day is relevant to ranking.
The site uses server-side database rules to require an authenticated, verified user for leaderboard submission and to reject obviously invalid values such as out-of-range scores or submissions for the wrong date. No client-side browser game can make cheating mathematically impossible on its own, but SizeDex uses both browser-side checks and backend validation to make ordinary leaderboard abuse more difficult.
Independent fan project
SizeDex is an unofficial, independent fan project. It is not affiliated with, endorsed by, or sponsored by Nintendo, Game Freak, Creatures Inc., or The Pokémon Company. Pokémon names, characters, designs, and related marks belong to their respective owners.
The original parts of SizeDex are the game concept and implementation, daily challenge logic, scoring presentation, interface, leaderboard system, statistics, site branding, and the written explanations on this website. The purpose of the project is to create a distinct interactive way to explore Pokémon scale rather than to present itself as an official Pokédex or official Pokémon service.
How the site is supported
SizeDex may display advertising to help cover hosting, development, database, email, and maintenance costs. Ads are intended to support the site without becoming the main purpose of the page. The game and original explanatory content remain the core of SizeDex. Advertising and analytics technologies are described in the Privacy Policy.