Did you know English Stirrups come in a variety of sizes? 
The standard adult size is 4-3/4". This is the width measured between the branches. Kid sizes stirrups can range from 4" - 4-1/2". Occasionally you can find oversize stirrups at 5".
To fit your stirrup properly, you want to be able to have a finger width between the branches. If it is too tight you can risk your put getting caught in the stirrup which raises the risk of getting dragged.
