Contact

Corrections especially welcome. If a number here is wrong, it is probably wrong in a way that affects every size, and we want to know.

Reporting an error

This is the most useful message you can send. Values on this site are generated from formulas and standard tables rather than entered by hand, which means an error is rarely isolated — if one figure is wrong, the same fault usually affects every size on the site. Fixing it at the source fixes all of them at once.

The most helpful report includes:

• The page URL
• Which value looks wrong, and what you believe it should be
• Your source, if you have one — a standard, a handbook, or a manufacturer's chart

Requesting coverage

If a thread series, fastener type or specification you need isn't here, say so. Pipe threads, ACME, Whitworth, washer and nut dimensions, thread-insert drill sizes and shear strength are all on the roadmap, and requests move things up it.

Advertising and commercial enquiries

Display advertising on this site is sold through automated advertising exchanges rather than directly. We do not accept paid guest posts, sponsored links, or paid placement in the reference data.

Response time

This is a small independent site, not a company with a support desk. Corrections get attention quickly because they matter. Other messages may take a few days.