How to measure for a shower curtain
A shower curtain should be wider than the shower since the curtain hangs in folds rather than hanging taut.
Measure your shower from one end of the shower curtain rod to the other. Then, add at least 12 inches to that measurement. Add more than 12 inches to create a billowy, rippled effect to the curtain even when closed. Divide that measurement by 2 to calculate how wide your curtain panels should be.
Our shower was 60 inches long, so we used curtain panels that were altogether 100 inches wide (50 inches wide per panel) because I wanted a billowy, rippled look.
Measure the height from the shower curtain rod to the floor to calculate how long your curtain panels and liner should be as well.
Related: Best Luxury for Less Amazon Curtains & Window Shades