How to measure paprer required

[mkb]

Hi all,
I'm papering hall stairs and landing with paper that has to be specially ordered and extras can't be taken back. Is there a way that I can measure so that I can order the exact amount of rolls. It's 25 quid a roll so want to get it right. cheers.

 

[dave1953]

Gonna depend on the pattern drop of the paper and the roll length as some specialist papers seem to be a bit reserved in their total length on the roll