Since I taught science for 30 years, I’m comfortable with metric units. (But when I rode my Harley to Canada, I was planning to claim the opposite if I’d been stopped for speeding! I never was though) I have an app on my smart phone to quickly convert between the two systems, so I cheat on it now. As said in an earlier post, 6.35 mm is the exact conversion for 1/4 inch.