There are a number of ways to measure hands for gloves. For gloves that I make, I use the following measuring method. You can also refer to the included YouTube video lower down.
As usual, there is no one universal glove sizing. I use the following Glove Sizes (sourced from LeatherGlovesOnline). Reproduced below:
Glove Sizes Chart
So as from today (24 May 2017), all the gloves I create will be using this method of measuring hands and the Glove Sizing Chart above.
In-between Sizes?
For a snug fit, go up one size.
For a normal fit, go down one size.
How to Measure Your Hands for Gloves
Reference:
• wikiHow: 3 Ways to Measure Hand Size