Knee breeches were a common pant in the 18th century, and are appropriate for French and Indian War through the American Revolution. These are made of a very nice medium weight 80/20 linen cotton with matching covered buttons and fit true to waist size in inches.
Additional sizing information:
The size of the breeches is in inches with the gusset completely closed. In other words, the size is the smallest the waist will go. For example, if your measurement was 37 inches, you would wear a size 36 breeches.
To find this number, measure around your waist where the breeches will sit (should be between the top of your jeans and your belly button).