I use that site often. I have only used the free calculators though. I'm a general builder so I need to know more than just how much plaster I need for a few walls. I need to know stuff like how much concrete or ballast and cement I'll be using on site. How many lorry loads of excavation material I will be digging out. How much sub-base I need etc.Anyone seen this? Only thing that springs to mind is mats cost - haven't really looked at it properly but folks have different prices depending on merchents (unless it goes on RRP)