I am making my 14 year old granddaughter a crossbody purse, just using my own pattern. How long should the strap be? Thank you for your information.

I made my daughter one and just used the width of the fabric for the strap.

That was what I had in mind when I started this project. Just got 1/2 yard of two different fabrics, which would have been plenty, except instead of cutting the strap first I cut the other pieces first. And I cut them off the end making the piece now 30 inches instead of 45 inches. Now will have to piece the strap. Maybe that's why you should use a pattern.lol

I always just took a measuring tape and flung it over my shoulder and across my body till hit felt right to me.

This. How low does she want it to hang?

My solution lately is to make the strap adjustable. You can pick up the sliders at Joann's. That way if she changes her mind and wants a shoulder bag she can shorten it.