This is an easy way to check the measurement of a roll of vinyl.
You are hoping that there is, say 24.5 metres. And you do not want to roll the whole roll out merely to find there is only 10 metres left.
The method above work well, and will record an accurate measurement within about 30cm.
Firs step Find yourself an A3 piece of paper, Most layers have access to a DUNLOP measuring planner. perfect for the job intended.
2nd Step simply fold it in half
3rd Step roll in into a circlend
4th Step Insert and ensure a tight fitting
5th Step Mark the inside measurement
6th Step Mark the outside measurement
Add the two measurements together
31.2 cm
73.5 cm
= 104.7 cm
Now all you have to do is count the number of coils starting from the inside (start of the coils) working your way to the outside)
Mutiply Half of 104.7 = 52.35 x 18 = 9.42
I never count the leftover bit