Curtain fabric width - please help a numpty

[thetideishigh]

I need to know what width of fabric I need in total for curtains to put up at a window which is 48" (inches) wide.

They are intended to be simple, tape top, very slightly gathered curtains and I have an old single door curtain that I'm hoping could be split into a pair of curtains for this window but it's hard to see if it will look odd/like there isn't quite enough fabric.

It doesn't have to drape and fold elegantly but the curtains do need to meet to block out the light in summer.

Can someone with a bit of knowledge help me here ?

How wide is the door curtain flat? The minimum for curtains is the width of the curtain rail (not window) plus 50%. A lot are width plus 100%.

Aah, thanks for that HettyA.

Fortunately I have now measured the door curtain flat as you suggested and find that I have 90" of fabric (width wise) to work with so it should be plenty. I don't know why I thought I only had 70" for some reason.