Size Duel
Daily duels, ten a day
269 things from an electron to the Sun: lengths, heights, mountain heights and masses.
No streak yetPractise by category
Two things.Pick the bigger one.
Then see them side by side, drawn to the same scale, with a person for comparison and a note on why it surprises people. Ten duels a day in each of four decks, every answer checked.
Four decks, one duel
Every deck uses the same rules: one named measure, a clear gap, checked sources. Your streak for each deck is kept separately.
Older Than
Daily duels, ten a day
350 inventions, buildings, books, places and events. Which came first?
No streak yetPractise by group
Population Duel
First daily on 25 October 2026
194 countries, World Bank estimates for 2025. Which has more people?
No streak yetPractise by region
Further North?
First daily on 25 October 2026
382 cities around the world. Which one lies further north?
No streak yetPractise by region
How a duel works
One question, one measure
“Which is taller?” compares heights only; a giraffe never meets a lorry on weight. Tap a card, or press 1 or 2.
See it to scale
Both things appear at their true size next to each other, with a person, a bank card or a scale bar for comparison. Dates go on a time ruler, people become figures and cities sit on a globe.
Learn the surprise
A one-line note says why the answer catches people out. Every item has its own page with its sources.
Questions
Size Duel is a small, honest game: no account, no ads, every fact sourced.
What is Size Duel?
A free two-choice game about the real world. Two things appear: pick the longer, taller, higher or heavier one. Then both are drawn to the same scale next to a person or a bank card, with a short note on why the answer surprises people.
What are the other decks?
Older Than asks which of two inventions, buildings, books or events came first and shows both on a time ruler. Population Duel asks which of two countries has more people (World Bank estimates for 2025) and draws both as figures. Further North? asks which of two cities lies further north and puts both on a globe.
Is it fair?
Every duel compares one named measure, like height with height, never height with weight. Sizes must differ by at least 15%, populations by at least 10%, dates by at least two years and cities by at least one degree of latitude, and ranges must not overlap, so natural variation never decides the answer. Each value was checked against two sources or comes from a checked open dataset, listed on its page.
How does the daily work?
Each deck has ten duels a day, the same for everyone, changing at midnight UTC. Finish on the day to grow that deck’s streak; a round you start before midnight still counts if you finish within two hours after. Past days are in the archive and never change your streak.
What is the endless streak?
Duel after duel until your first miss. It never repeats an item until it has shown the whole deck, and it gets harder as you go.
Can I play it on stream?
Yes, every deck. Streamer mode makes the type bigger, keeps the bottom-right corner free for a webcam, mutes sounds by default and adds a “chat, vote now” countdown before you can answer. It has no chat connection: chat votes in your chat, you click.
Does it work offline?
Yes. After your first visit every deck and every drawing are kept on your device.