You won't find these calculations on your CRP-1 but here's a pretty good way of determining if you are ok to drive : -
For every unit of alcohol you intake your body will need 1 hour to process. For example if you intake 8 units you will be 'clean' in 9 hours. (You start the unit count down 1 hour after consuming the first unit)
Your body will still process the alcohol whilst you are drinking and you do not need to start the count down after you have finished drinking.
Now for men, if you work out how many units you have still in you after subtracting the number of hours, multiply this amount by 7. This will give you your breathalyser reading.
For example if you started drinking at 1200 and consumed 8 units of alcohol by 1700, start the unit countdown at 1300 and this gives you 4 hours. Subtract 4 (hours) from 8 (units) and this leaves 4. Multiply the 4 by 7 and you will get 28, which is what your breathalyser reading will be.
The multiplier for women is 11.
Although everyone is different this method is fairly accurate and is a good indicator of whether you are ok to drive. The legal limit for driving is 35, so 5 units in your system would make you borderline. I would suggest that for flying you should have a zero rating.