Tipping
Tip on the pre-tip bill
One multiplication, applied to the bill rather than to anyone's share. The rate is the percentage written as a decimal, so eighteen per cent is 0.18.
The Formula
tip = bill x rate
One multiplication, applied to the bill rather than to anyone's share. The rate is the percentage written as a decimal, so eighteen per cent is 0.18.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| bill | The pre-tip bill | currency | The base the percentage applies to, 240 in the worked case. |
| rate | Tip percentage as a decimal | dimensionless | 18 per cent is 0.18, 20 per cent is 0.20, 15 per cent is 0.15. |
| tip | The gratuity for the whole table | currency | For 240 at 0.18 this comes to 43.199999999999996. |
What Each Symbol Means
billcurrency
The pre-tip bill
The base the percentage applies to, 240 in the worked case.
ratedimensionless
Tip percentage as a decimal
18 per cent is 0.18, 20 per cent is 0.20, 15 per cent is 0.15.
tipcurrency
The gratuity for the whole table
For 240 at 0.18 this comes to 43.199999999999996.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate a split bill page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate A Split Bill, filed under Everyday Life. Every number the guide produces comes from substituting into this one line.