How the tip is calculated
The tip is a percentage of the bill: bill × percentage ÷ 100. On a bill of 64.50 with a 10% tip, the tip is 6.45 and the total is 70.95. A quick mental check is to find 10% by moving the decimal point one place to the left, then double it for 20% or add half of it again for 15%. The calculator does the exact sum for any percentage, including unusual ones such as 12.5%, and shows the tip and the new total side by side.
Splitting the bill fairly
When a total does not divide evenly, someone has to pay the odd cent. For example, 100 split between 3 people is 33.333…, which cannot be paid. Instead of rounding everyone to 33.33 and leaving the bill one cent short, the calculator works in cents (or fils for currencies with three decimals) and tells you, for instance, that one person pays 33.34 and two pay 33.33. Added together the shares always equal the total exactly.
Rounding the total or each share
Paying in cash is easier with round numbers. "Round the total up" raises the whole bill to the next 1, 5 or 10 and then splits it, which suits one person paying the bill. "Round each share up" gives everyone the same whole amount, which suits a group where each person pays separately. Either way the extra goes to the tip, and the calculator shows the tip percentage that results, so you know if rounding has made the tip much larger than you meant.
Tax, service charges and local customs
Some people tip on the amount before tax and some on the final amount; enter whichever figure you want to base the tip on. Many restaurants add a service charge to the bill, so read it before adding a tip on top. Whether a tip is expected, and how much, varies a great deal between countries, cities and types of venue, and can change over time. We do not list percentages by country because we could not confirm them from reliable sources; if in doubt, ask locally or check the venue's own policy.