Q What's the best way to calculate and compensate for wastage?  I can't spend hours trying to keep track of my food wastage everyday.

I completely agree that spending hours on food wastage is an inappropriate use of time. However, it must be a matter for consideration so I recommend breaking wastage into categories with each category requiring a different perspective.

The first category would be "guest satisfaction," i.e., steak returned because it was overcooked, etc. Waste of this nature should be rung up in the point-of-sale system and recorded under the same caption of "Guest Satisfaction."

The second category would be for major catastrophes, i.e., a refrigeration breakdown that resulted in a significant loss, etc. This information would be recorded on the books under the category for "Wastage."

The last category would be "minor inefficiencies," i.e., scrap portions, accidents, etc. I would not recommend tracking these.

By recording the first two categories separately, the actual food costs are not affected because the items have been accounted for so that would only leave the third category unaccounted for which should be insignificant.
Since the chef has costed out his or her menu, any variation from the targeted food costs would show up and part of that variance would be this wastage.

If the variance is significant, further analysis would be necessary; however, it would be impractical to go through the work of keeping track of wastage unless there is a problem that requires this analysis. In other words, there may not be a problem so I would not recommend doing this work unless a problem seems to exist.