SPLIT THE BILL

WHAT IT WORKS OUT

Total per person, tip per person and the grand total, from the bill amount, the tip percentage and the number of people. It handles the part everyone gets wrong at the table: whether the tip goes on the pre-tax or post-tax figure, and what each person actually hands over once it is rounded.

TIP ON THE TOTAL OR THE SUBTOTAL

Tipping on the pre-tax subtotal is the technically correct convention, since tax is not part of the service. In practice most people tip on the full total because it is easier and the difference is small — on a 100 bill with 20 percent tax, tipping 15 percent on the total costs about three more. Either is fine. Being consistent matters more than being right.

TIPPING VARIES ENORMOUSLY BY COUNTRY

• United States — 18 to 20 percent is standard, servers are paid assuming it
• Most of Europe — service is often included; rounding up or 5 to 10 percent is plenty
• Japan — tipping is not customary and can be awkward
• Always check the bill for a service charge before adding anything on top

THE FAIRNESS PROBLEM

An even split is simplest and works when everyone ate roughly the same. It stops being fair fast when one person had tap water and a salad and someone else ordered the steak and two bottles of wine. If the gap is big, split by what each person ordered and add the tip proportionally. The even split is a convenience, not a rule — and nobody should have to ask twice.

Rounding up to a clean number per person is normal and usually the fastest way to close the whole thing out.