Does anyone know where I can find a reference on the scale of maps/characters?

Like, I want to know how much 1 unit in the w@w radiant is in metric or inches.
I want to remake a source engine map, which source engine maps have "hammer" as units and 1 hu is 1.9cm.
But how do I find out how much 1 unit is in the radiant?
I know that uh the radiant has different grid sizes, but for example, how much is 1 unit on a grid size of 8 in metric?

hammer and radiant both use the same grid size and if you want to work on a remake of a source map, consider porting it with this tutorial

https://ugx-mods.com/forum/index.php/topic,2997.0.html

Oh, this will help. Thanks.