Tip calculator
American practice is to tip on the pre-tax subtotal, though tipping on the total is common and nobody objects. On a $84.50 bill the difference at 18% is roughly a dollar. If the bill already carries a service charge, that is the tip.
Multiply the bill by the tip percentage and divide by a hundred to get the tip, then add it to the bill for the total. Fifteen to twenty per cent is the usual range for table service in the United States; much of Europe rounds up instead, and in Japan tipping is not expected at all.
How to use it
A quick way to do twenty per cent in your head: move the decimal point one place left to get ten per cent, then double it. Eighty-four fifty gives 8.45, doubled to 16.90. For eighteen per cent, take the twenty per cent figure and subtract a tenth of it.
Questions
Convention says tip on the pre-tax amount, but tipping on the total is normal and the difference is small. This calculator tips on whatever number you type in.