What is the minimum diameter of round watches and mechanical watches worn by men now?

To tell the truth, there are no mandatory binding regulations in this world.

Generally, men's watches are 33-40mm and women's watches are 20-30mm. Now there are 30mm-35mm neutral watches as fashion watches, which are beautiful for both men and women.

I have a business watch of 35, an electronic watch of 38 and an electronic sports watch of 40.