This means that the final size of any tarp can be as much as 30cms shorter than the size stated. You need to factor this in when ordering your tarp.
It's of course best to err on the side of caution, so if you think things might be tight it's best to order a slightly larger tarp size to avoid dealing with a shortfall. Green Water proof Polyethylene 12.0 metres x 20.0 metres Heavy Duty Weather proof 12.0 metres x 20.0 metres Water proof Polyethylene Green. This item is in the category "Home, Furniture & DIY\DIY Tools & Workshop Equipment\Other DIY Tools & Workshop Equipment". The seller is "toolsmartltd" and is located in this country: GB. This item can be shipped worldwide.