Frequently asked questions

Guessroo is a set of free daily guessing games about the real world. Sizeroo asks how big things are, Farroo how far apart two places are, Weighroo how heavy things are, Speedroo how fast things go and Yearline when famous events happened. Each game gives you 5 questions a day and takes about a minute.

Yes. Every game is free to play in your browser on a phone, tablet or computer. There is nothing to download and no account to make. The site is paid for by advertising.

Every game gets 5 new questions at midnight in your own time zone. The puzzle number at the top of the game goes up by one each day.

Yes. Everyone in the world gets the same 5 questions on the same date, which is what makes comparing scores and the daily leaderboard fair.

Each question is worth up to 100 points, so the best day is 500. Sizeroo, Weighroo and Speedroo score by ratio: within 10% of the answer is 100 points, twice too high or too low is about 70 and ten times off is 0. Farroo is stricter: within 5% is 100, half or double is 50 and four times off is 0. In Yearline the exact year or one year off is 100 points, and each extra year off costs 2 points.

Real things range from tiny to enormous, so the size, weight, speed and distance scales are logarithmic: every rung is ten times the one before. That way a guess of 300 metres for something that is 330 metres scores as well as a guess of 3 millimetres for something that is 3.3 millimetres.

A small clock starts when each question appears and stops when you lock in your guess. Your time for the day is the total of all 5 questions. Time never changes your score; it only breaks ties on the leaderboard, so a quick 400 ranks above a slow 400.

When you finish your 5 questions, your score and time are sent to that day's leaderboard for the game. Players are ranked by score, then by time. You can see your rank, the share of players you beat and the top 10 from the statistics button at the top of each game. Only your first finished game of the day counts.

So that nobody has to sign up or type a name, Guessroo gives each device a random name such as Swift Wombat 42. The name stays the same on that device every day. Nobody can choose a rude name, and the name says nothing about who you are.

Your games played, average and best score, streaks, fastest time and score spread are saved in your browser on this device. If you clear your browser data or switch to another device, they start again from zero.

Tap the sun or moon button in the top corner of any page. Guessroo follows your device setting until you choose, then remembers your choice.

Sizes, weights and speeds come from official figures, published records and encyclopedias. When something varies, such as the length of a blue whale, we use a typical adult value and say so in the fact. Farroo distances are calculated as the crow flies, along the surface of the Earth between city centres. Yearline uses the commonly accepted year of each event.

Yes. Every question has its own answer page with the figure, a short fact and comparisons. See all sizes, distances, weights and speeds from the links at the bottom of each page.

After your fifth question, tap Copy my result. It copies your score, time and a row of coloured squares, one for each answer, without giving away the questions.

Please tell us at [email protected] with the question and, if you can, a source. We check every report and fix mistakes quickly.