SizeGuess

SizeGuess tests how well you can picture the real size of things. On each round a dark green silhouette stands on the ground line with its real measurement written underneath, and a red silhouette of something else stands beside it. You pull the corner of the red one, drag a slider or press the arrow keys until it looks the right size next to the reference, then lock in your guess.

The daily five is the shared challenge: five rounds, numbered by day, the same for everyone, with a running score out of 500. The label above each object says which dimension counts, height for a tower or length for a court, so reading it before you resize matters. After each guess the true size is drawn in, and the game gives you a comparison to carry into the next round.

Beyond the daily, the site has Unlimited play, a Survival mode and a Countries mode where you compare the size of nations, plus a library of collections: animals, dinosaurs, landmarks, vehicles, space, everyday objects, geography and nature. A separate comparison tool lets you line up real objects, and your own height, on one scale. You can switch the units between metres and feet and inches.

The daily plays with no sign-up, and your scores and streak stay in your browser. A friend challenge sends the same five rounds to people you pick and keeps their nicknames and scores on one shared table. The site says it is independently made and takes its resizing idea from Size It Up. Each object comes with a note on where its measurement was found, and the page loads Google AdSense. It suits anyone who likes estimation games but would rather judge by eye than type a number, and the objects range from a tennis ball to planets.