Box office means two things and the context decides which: a place in the venue, and a number on a report.
The report
The number that matters at settlement. A box office report lists tickets sold at each price, comps, guest list, and the split between presale and walk-up. Ask for it as a PDF, with the ticketing company's own figures behind it.
Reading one
- Sold: paid tickets, the only ones a percentage is calculated on
- Comps: free tickets, usually capped in the contract
- Kills: places held back for production and sight lines
- Drop count: how many people came through the door on the night
Sold and attended are different numbers. A show at 90 percent Sell-through with a heavy guest list can feel fuller than it paid.
Fees
In most of Europe the advertised ticket price includes a service fee the venue or ticketing company keeps. That comes off before any percentage is worked out.