Thanks yes you are right about the existing error in the sheet (the perils of trying to replicate a problem for the purposes of illustration...)

Anyway happily this one is now sorted too. You are a mine of useful information! I can't pretend that I understand what is going on in the sumproduct formula though, although I managed to adopt it for the more complicated sheet I'm using it in. If you have time, I'd love to see an explanation for the formula - should reduce further pestering questions in the future ;-)

Thanks again

TM