[header] How to buy a shower curtain [title] Select a liner size. [step] Measure your shower to determine the size of liner and shower curtain you will need. You will want your liner to fit in your shower for appearance and so it does its job of preventing water from escaping into your bathroom. 
Most liners for a standard size shower are 70 by 72 inches (1.8 by 1.8 m). [substeps] Make sure your liner stretches between the two walls and reaches down to the floor so no water escapes.