How to Work Out a Tip Without a Calculator
Working out a tip feels harder than it is, mostly because it happens at the end of a meal with other people watching. The good news is that every common tip rate can be built from one easy number: 10% of the bill. Once you can find that in your head, the rest is addition.
This guide shows the shortcut, a way to round sensibly, how to split a bill between friends, and the questions people most often get stuck on. Tipping customs differ widely between countries and venues, so treat the percentages here as arithmetic, not etiquette advice.
The 10% trick
To find 10% of any number, move the decimal point one place to the left. 10% of 64.80 is 6.48. That single step is the foundation for the other rates:
- 10%: move the decimal one place left.
- 20%: find 10% and double it.
- 15%: find 10%, then add half of it (5%).
- 5%: find 10% and halve it.
Worked example, bill of 64.80: 10% is 6.48. A 20% tip is 2 × 6.48 = 12.96. A 15% tip is 6.48 + 3.24 = 9.72. If you want a rounder figure, 13.00 and 9.75 are close enough for most tables.
tip = bill × rate ÷ 100The exact formula behind every shortcut.
A quick-reference table
These round bills are easy to scale: for a bill ten times larger, move the decimal one place right.
| Bill | 15% tip | 18% tip | 20% tip |
|---|---|---|---|
| 20.00 | 3.00 | 3.60 | 4.00 |
| 40.00 | 6.00 | 7.20 | 8.00 |
| 60.00 | 9.00 | 10.80 | 12.00 |
| 80.00 | 12.00 | 14.40 | 16.00 |
| 100.00 | 15.00 | 18.00 | 20.00 |
Splitting the bill
Add the tip first, then divide, so everyone covers the same share of both. Dividing the bill and the tip separately gives the same answer but takes two steps instead of one.
Worked example: four friends, a bill of 86.40 and an 18% tip. The tip is 86.40 × 0.18 = 15.552, which rounds to 15.55. The total is 86.40 + 15.55 = 101.95, and each person pays 101.95 ÷ 4 = about 25.49. Because 25.49 × 4 is 101.96, one person can round down by a cent if you want the table to add up exactly.
If one person ordered much less, it is usually fairer to split the tip by each person's share of the bill rather than evenly.
Before or after tax?
Many people calculate the tip on the pre-tax amount, because the tax is not part of the service. Others tip on the total because it is simpler. Both are common, and the difference is small: on a 50.00 meal with 8% tax, a 20% tip is 10.00 on the pre-tax amount and 10.80 on the total.
If the bill already includes a service charge, check what it covers before adding more. In some places it replaces the tip entirely; in others it goes to the house and a tip is still welcome.
Rounding sensibly
- Round the tip, not the bill: 15.55 becomes 16 if you prefer round numbers, which is about 18.5% here.
- Round up for good service and to the nearest whole unit for quick service.
- If you pay by card, check the total on the receipt before you add a tip, so you do not tip on a figure that already includes one.
- Tip Calculator: Enter the bill, choose a tip percentage and, if you are sharing, the number of people. You get the total, the tip, and each person's share, with optional rounding up.
- Percentage Calculator: Pick the question you need answered, enter two numbers and get the result instantly. The guide below shows the formula behind each mode.
This article is general information, not professional advice. See our Disclaimer and Editorial Policy.
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