The right tap drill, in one tap
Pick 1/4-20 or M8 and the drill appears at a size you can read from across the bench: number, letter, fractional or metric, with its decimal size and thread percentage.
Tap drill chart · UNC · UNF · Metric
The tap drill chart in your pocket.
The right tap drill for any common thread in one tap. Cut and form taps, clearance holes and thread identification. Works offline, no account, no ads.
Every common thread
UNC and UNF from #0 to 1 inch, ISO metric coarse and fine from M1.6 to M30. Search or browse the full chart.
Cut and form taps
Form taps need a bigger hole. Switch between them, or set your own thread percentage for hard or deep holes.
Clearance holes
Close, normal and free fit for the same fastener, straight from ISO 273 and published inch charts.
Your own drill set
Tick the drills you own and every answer snaps to the closest one you actually have.
Identify a thread
Measure a bolt with calipers and a pitch gauge, and see which threads it can be, look-alikes included.
Support
Questions, a wrong-looking number or a thread you need? Email support@retroselfie.me. We read every message and usually reply within two working days.
- Where do the numbers come from?
- From published standards and charts: ANSI drill sizes, the unified inch and ISO metric thread series, ISO 273 clearance holes and Machinery's Handbook formulas. If a value is not in a verified table, the app says so instead of guessing.
- Does it need the internet?
- No. Every lookup works offline. The internet is only used to buy or restore Pro and, if you allow it, to share anonymous usage.
- Is Pro a subscription?
- No. Pro is a one-time purchase, shared with your family through Family Sharing. Restore it any time from the Pro screen.
- What is free?
- Cut tap drills for the everyday coarse threads: UNC #4 to 1/2 and metric M3 to M12, plus favorites and the drill finder.