Also called Covers
A cover is one guest served. Restaurants count covers rather than bills because a table of four is four covers on one bill — and staffing, prep and revenue all scale with guests, not with tables.
Covers are the standard unit of volume in hospitality. Revenue per cover, or average spend per cover, is more stable than average bill value, because bill value moves with party size while spend per head does not.
Counting covers also makes capacity planning possible: seats multiplied by turns gives your theoretical maximum covers for a service, which is what break-even calculations are built on.
Example
A restaurant serving 120 guests across 45 bills in an evening did 120 covers, not 45.
Free tools for this
MinimalPOS handles orders, kitchen, billing and reporting in one flow.