THe wider you can get, the faster it'll go on and cleaner it'll look. But, the narrower you go, the easier it is to "repair" if it becomes damaged.
YOu always buy more than you need, but if you have no clue how much you need, here's the skinny.
1. Measure the length of the pipe along the "outside" of the bends (the widest part).
2. Decide which width you prefer and divide it in half. (2" wrap will give you a value of 1", 1" will give you a value of 0.5".)
3. Measure the circumference of the pipe.
4. DIvide the length of the pipe by the number you got in step 2.
5. Multiply answer 3 by answer 4.
6. Add 1 if you are a dependent or receive social security or have clipped your toenails in the last three hours.
7. Repeat 1-5 for each runner of pipe.
I kid, but this you should be able to enter it like this:
runner length
pipe circumference X -----------------------
wrap coverage
Repeat this step for each runner and add about 6-8" for each section to allow for tuck if you prefer to have neat-looking ends.
This is obviously for if you have to mail-order the stuff or something, and want to get it right the first time without buying too much. Otherwise, just hit up a brick-and-mortar shop, buy four packages and return what you don't need.
