One photo → fastener type, standard (DIN · ISO · UNC · NPT), size range and where to buy the replacement. The digital thread checker — honest answers, never made-up precision.
Verified on our labeled hardware-store benchmark, July 2026. We publish our numbers — ask any other scanner app for theirs.
No calipers, no thread charts, no guessing at the store counter.
Any coin in your pocket becomes the ruler — the app knows each one's exact diameter (a quarter is 24.26 mm). Even sharper: any plastic card — loyalty, transit, hotel key. We use only its standard size, never its numbers.
The AI reads head shape, drive, thread profile and the coin next to your part — then matches it against real DIN/ISO/ANSI spec tables, not vibes.
A confident match, a short list of likely ones, or two smart questions — with a size range, never a fake decimal point.
Scanner apps die by guessing — users measure the part, catch the lie once, delete forever. BoltSnap tells you exactly how sure it is:
When confidence is high and verified against spec tables: type, standard, size — one card, done.
When look-alikes exist (M8 vs 5/16"), you get the shortlist with one-line differences. The truth is in there — 100% of the time in our benchmark.
Thread pitch can't be read from a photo — anyone claiming otherwise is guessing. We ask two smart questions or hand you a free printable gauge.
Every answer can export a 100%-scale printable gauge: diameter circles, metric pitch combs, TPI combs — with a built-in ruler and a quarter-circle to verify your printer didn't cheat.
Download the gauge (PDF, free)The two tables everyone googles from the garage. The app knows every row offline — but bookmarks are free.
| Wrench | Bolt | Pitch (coarse) |
|---|---|---|
| 8 mm | M5 | 0.8 |
| 10 mm | M6 | 1.0 |
| 13 mm | M8 | 1.25 |
| 17 mm | M10 | 1.5 |
| 19 mm | M12 | 1.75 |
| Wrench | Bolt | TPI (UNC) |
|---|---|---|
| 7/16" | 1/4" | 20 |
| 1/2" | 5/16" | 18 |
| 9/16" | 3/8" | 16 |
| 3/4" | 1/2" | 13 |
| ⚠ M8 and 5/16" look identical — that's the trap the app catches | ||
No — and neither can any app, that's optics. BoltSnap narrows it to the diameter, then settles pitch with one question or the printable gauge. Apps that claim pitch from a photo are the reason this category has one-star reviews.
Photos are processed to identify your part and not kept. Contributing a photo to improve the recognizer is a separate, explicit opt-in — per photo, off by default.
Pure geometry: a card's long edge is 85.6 mm — about 3.5× a coin — so the size math gets sharper. Any no-name plastic works: loyalty card, transit pass, hotel key. We read shapes and sizes, never card numbers, and the photo isn't stored unless you explicitly donate it. Coins work great too.
First scans are free, then a small subscription. Cheaper than one wrong bolt run to the store.