GuesstimasterAbout Guesstimaster
Guesstimaster is a counting game for your phone camera. You guess how many. A machine counts. Then you find out who was right.
PlayHow to play
Take a photo of anything with a lot of the same thing in it: the bricks in a wall, the windows on a building, the cars in a parking lot, the grapes in a bowl, the sheep in a field. Type what to count, or pick one of the ideas. Then everyone who's guessing gets a short look at the photo (3, 5 or 10 seconds, or as long as you like) before it blurs out, and locks in a number.
Playing with friends? Tap Pass the phone after each guess. Every guesser gets the same short look, and the closest guess wins when you reveal the count.
How the counting works
While you guess, the photo goes to an object detector running on an RTX 5090 graphics card. You tell it what to look for in plain words and it finds every instance it can see. Detectors miss small things in a big photo, so it also looks closer: it splits the photo into overlapping tiles, finer and finer, counts each one, and stitches the results back together without counting anything twice. A dense brick wall or a packed fruit crate can take a few seconds.
The reveal rolls up like a hand tally counter and drops a dot on every one it found. The dots are there so you can check its work: it does miss things in very crowded scenes, and it will count a statue as a person.
When the graphics card is asleep, a backup counter (Claude, an AI model that can read photos) makes a careful estimate instead. Those counts say rough and come without dots.
Scoring
Accuracy is the smaller number divided by the bigger one. Guessing 900 when there are 1,000 scores 90%, and so does guessing 9 when there are 10, so a big wall is as fair as a small bowl.
| Guesstimaster | 97% and up |
| Sharp eye | 90% |
| In the ballpark | 75% |
| Rough guess | 55% |
| Wild guess | 30% |
| Shot in the dark | below 30% |
What counts
Only what is in the frame. Something cut off at the edge counts when enough of it shows to recognise. Reflections and pictures of things usually don't, though the counter can be fooled.
Your photos
A photo is held in memory just long enough to count it and is then thrown away. It is never written to disk, never shown to anyone else, and there are no accounts. Share cards are made on your own phone.
Who made it
Guesstimaster was built by Will Loughlin as part of 30 websites in 30 days.