Key takeaways
Tipping does not need an app. Start from 10 %, double it, halve it or add the two, and you can cover every common tip rate in a few seconds.
- 10 % of any bill is the bill with the decimal point moved one place left.
- 20 % is double that; 15 % is 10 % plus half of 10 %.
- Round the bill first; nobody tips to the cent.
Start from ten percent
Ten percent of a number is the number with the decimal point moved one place to the left. A bill of $64.80 becomes $6.48. Round it to $6.50 and you have a base to build on.
Double, halve, add
- 20 %: double the 10 % figure. $6.50 × 2 = $13.
- 15 %: add half of the 10 % figure to itself. $6.50 + $3.25 = $9.75.
- 18 %: take 20 % and subtract a tenth of the 10 % figure. $13 − $0.65 = $12.35.
A worked example
Your bill is $47.20. Ten percent is $4.72, call it $4.70. Twenty percent is $9.40. Fifteen percent is $4.70 + $2.35 = $7.05. Pick the rate you want and round to the nearest quarter.
Tax or no tax?
Custom varies by country. In the United States most people tip on the pre-tax amount, but the difference on a typical bill is under a dollar, so do whatever is quickest.
If the service was good, round up. The maths is a floor, not a ceiling.
Related questions
- How much should I tip on a $60 bill?
- Do you tip on the total with tax or without?
