Terms of use

1. Using the site

tapdrillsizechart.com is free to use, for any purpose, with no account and no licence fee. Look things up, print the charts, keep a card by the machine. By using the site you accept these terms; if you do not accept them, do not use it.

2. Accuracy, and its limits

I have taken real care with this data. Figures come from published tap and drill charts and the relevant standards, every percent of thread is recomputed from first principles at build time, and the build fails on a malformed or inconsistent record. Where a standard does not cover a size, the page says so instead of showing a number.

Even so, you should know:

• Published charts disagree. Tap makers use different formulas and round differently. Two reputable sources can give different drills for the same thread, and both are defensible.
• A chart does not know your job. Material, hole depth, tap style, machine rigidity, lubricant and required tolerance all change the right answer, and none of them are on this site.
• Form tap sizes are starting points. Every tap maker publishes its own. Use the one that came with your tap.
• Mistakes are possible. Checks reduce them; they do not eliminate them.

3. Verify before critical use

For anything structural, pressure-bearing, load-carrying or otherwise safety-critical, treat this site as a starting point and confirm the figure against your drawing or specification, the governing standard, and the documentation for the actual tap you are using. Where it matters, cut a test thread in scrap and check it with a thread gauge first.

4. No warranty

The site and everything on it are provided "as is" and "as available", without warranty of any kind, express or implied, including any implied warranty of merchantability, fitness for a particular purpose, accuracy or non-infringement. I do not warrant that the content is accurate, complete or current, or that the site will be available without interruption or error.

5. Limitation of liability

To the fullest extent the law allows, I am not liable for any loss or damage arising from your use of this site or reliance on anything in it. That includes broken taps, scrapped parts, damaged tools, lost time, lost profit, and any indirect or consequential loss, whether or not the possibility was foreseeable.

Nothing here excludes or limits liability that cannot lawfully be excluded or limited, including liability for death or personal injury caused by negligence, or for fraud.

6. The data

Thread dimensions, drill sizes and clearance values are facts and standards; I claim no ownership of them, and you are welcome to use the numbers. The site's own text, layout, drawings and code are mine. Quoting a figure or linking to a page is fine and welcome; republishing the written content wholesale is not.

Standards referenced by name, including ASME B18.2.8 and ISO 273, belong to their respective bodies. This site is not affiliated with, endorsed by or published by any standards organisation or tool maker.

7. External links

Links to other sites are offered as useful references. I do not control them and I am not responsible for their content, accuracy or availability.

8. Changes

These terms may change, and the date at the top will change with them. Continued use after a change means you accept the revised terms.

9. Getting in touch

Questions about these terms, or a correction to report, go to the contact page. Corrections are genuinely welcome.