Unwell Raptor
Thanks, I had just come back to add something along those lines.
My calculations are very very rough and only give an idea for the 'avarage' person (what ever that is)
The only reliable way is to buy a breath test machine and test twice, first to make sure you are under and the second to make sure you are 'going down' not up.
The ones we used to use cost around £700, or so we were charged if we lost one, if they are the same price or less then well worth buying I would think.