There are so many issues these days with whether a fastener is Imperial or metric that it really pays to have pitch gauges and learn to use them. I bought a combo set for about $5 that I keep in my tool box. Saves a lot of time by eliminating guesswork. The most common metric threads are .75, 1, 1.25, and 1.5 in the bolt sizes we most commonly deal with. Metric threads are measured in threads per millimetre whereas Imperial threads are measured in threads per inch.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.