I have a tin of buttons that belonged to my great-grandmother. I've wanted to use them, but was unsure of the size of each. I don't mind mixing, matching, and guessing, but I wanted to sort them by size, and didn't know what size to label each group.

I found this chart for button sizing at www.karimeaway.com:

https://www.karimeaway.com/files/buttonsizingchartexpanded.pdf

I printed it at 100% and labeled the sizes according to the chart. Now if a pattern calls for a 9/16" button, I'll have a clearer idea which ones to use.