XOR Just to let you know that you are a genius and should be upgraded to professional. I did as you said. The Maths need to be in the hundreds and thousands eg rather than 4.5 MTR it has to be 450.00 cm or lower. The input for the user would be 4.5 MTR but the calculations in the background must be in the smaller ratio. Just add a round up or round down depending in the side of safety you require and hey presto correct SUM up brilliant consider this solved but I cant mark it as solved as it wont let me or is it just me