Take your measurement around your leg at the location where the garter will be worn - measure where the BOTTOM of the holster would be.
The holster is made of military grade elastic. It is normal for elastic to "relax" a little after wearing and laundering. Choose a size that is snug but not too tight.
|GARTER HOLSTER SIZE||LEG SIZE (where bottom of holster will be|
|Small||15" - 18"|
|Medium||18" - 21"|
|Large||21" - 24"|
|XL||24" - 27"|