Should you tip before or after tax?

Custom differs and this page will not tell you what to do — it shows both so the choice stays yours. Tipping on the pre-tax amount is the more commonly given advice, on the reasoning that the tax went to the state rather than to the person who served you. The gap is a few percent of the tip, not of the bill.

How do you split a bill unevenly?

This page splits evenly, which is what most tables want. For an uneven split, run it once per person against their own share: a percentage applies the same way to any amount, so four separate calculations come to the same total as one.

Why does the card machine suggest more than this?

Two reasons, and they compound. It usually calculates from the post-tax total, and its preset buttons often start at 20% or 22% where the traditional default was 15%. Both are defaults somebody else chose for you.

Money

Tip Calculator

Enter the bill and the percentage. Tax is kept separate, because tipping on tax is a choice.

The formula

tip = bill before tax × percent ÷ 100

total = bill + tax + tip

each person pays = total ÷ people

Worked example

An $84.50 meal with $7.19 of tax, tipping 20%, split two ways

84.50 × 0.20 = $16.90 tip
84.50 + 7.19 + 16.90 = $108.59 total
108.59 ÷ 2 = $54.30 each
Tipping on the taxed total instead would be $18.34 — $1.44 more

Where this goes wrong

Tipping on the tax without meaning to

Card terminals normally calculate their suggested tips from the total after tax, because that is the number they have. On an $84.50 meal with $7.19 of tax, 20% of the bill is $16.90 and 20% of the taxed total is $18.34 — an 8.5% larger tip than the one you thought you were leaving. Neither figure is wrong; only one of them is the one you chose.

Questions

Should you tip before or after tax?: Custom differs and this page will not tell you what to do — it shows both so the choice stays yours. Tipping on the pre-tax amount is the more commonly given advice, on the reasoning that the tax went to the state rather than to the person who served you. The gap is a few percent of the tip, not of the bill.
How do you split a bill unevenly?: This page splits evenly, which is what most tables want. For an uneven split, run it once per person against their own share: a percentage applies the same way to any amount, so four separate calculations come to the same total as one.
Why does the card machine suggest more than this?: Two reasons, and they compound. It usually calculates from the post-tax total, and its preset buttons often start at 20% or 22% where the traditional default was 15%. Both are defaults somebody else chose for you.