How to measure yourself for strap-ons?
To measure a vagina, you will need a vibrator (if possible), or an alternative object which is long, clean and has a smooth surface.
To begin, either you or your partner lay on their back with legs spread. The vagina needs stimulating at this point. Once aroused, you can start sliding the vibrator or alternative object into the vagina. Once the furthest point is reached in the vagina, mark this on the vibrator/ alternative object.
This is the strap on length (for the dildo or vibrator) which the vagina can handle. To measure circumference or girth, fingers can be slid into the vagina until the limit is reached.
When this point has been reached, wrap the tape measure around the fullest point to find the circumference/girth that the vagina can accommodate comfortably.
How Do You Measure Sex Toys?
Generally speaking there are four measurements you should be familiar with.
Length: The vertical length of the toy from the two farthest points. We sometimes refer to this as total length as well.
Insertable Length: The length of the toy designed to be safely inserted.
Width (or diameter): The distance between the two sides of the toy.
Girth (or circumference): The circumference of the toy which is relevant to insertable toys.