Tip Calculator
Enter the bill, a tip percentage, and how many people are splitting it. Straightforward arithmetic with two details that actually change the number: whether you tip on the pre-tax or post-tax amount, and whether a service charge has already been added.
How to use it
- Enter the bill amount.
- Set the tip percentage and the number of people splitting.
- Read the total per person, tip amount, and grand total.
Pre-tax or post-tax
Tipping on the pre-tax subtotal is the conventionally correct approach, since the tax is not part of the service. Tipping on the post-tax total is more common in practice, mostly because that is the number printed largest on the bill.
The difference is modest. On a $100 subtotal with 8 percent tax, an 18 percent tip is $18.00 pre-tax and $19.44 post-tax — about $1.44. It is not worth an argument, but it is worth knowing that a card terminal offering suggested percentages is almost always computing them on the post-tax total, and sometimes on the total including a service charge.
Where it does matter is at high bill values and in high-tax jurisdictions. On a $500 bill at 10 percent tax the same choice is a $9 difference, and at 25 percent gratuity on a large group bill the compounding of tip on tax becomes noticeable.
Service charges and automatic gratuities
Many bills already include a service charge, particularly for large groups, and tipping on top of it means paying twice. The line is easy to miss because it appears among the taxes and fees rather than near the total.
The terms vary and matter. An automatic gratuity, commonly 18 or 20 percent for parties above six or eight, is a tip and no further tip is expected. A service charge may or may not go to staff depending on jurisdiction and house policy, which is a reasonable thing to ask about. In much of Europe service is included by law or convention and additional tipping is optional and small — rounding up rather than a percentage.
The practical habit is to read the itemised lines before the total, particularly on a group bill, and to note that suggested-tip percentages on the terminal are frequently calculated on a total that already contains the service charge.
Mental arithmetic that works
Moving the decimal one place left gives 10 percent. Everything else builds from there.
On a $86.50 bill:
- 10 percent is $8.65.
- 20 percent is double that, $17.30.
- 15 percent is 10 percent plus half of it: $8.65 plus $4.33, which is $12.98.
- 18 percent is 20 percent minus a tenth of the 20 percent: $17.30 minus $1.73, about $15.57.
- 25 percent is a quarter, so divide by four: about $21.63.
Splitting a bill fairly
An even split is simplest and is usually fine when orders were comparable. It stops being fine when they were not, and the discrepancy is often larger than people assume — two people drinking wine can easily account for half a table bill.
Splitting by item is fairer but needs a decision on the shared elements. The usual approach is to allocate individual items to individuals, then divide appetisers, shared sides, tax, and tip proportionally to each person subtotal rather than evenly, since tax and tip scale with what was ordered.
One practical note on card payments: many restaurants limit the number of cards they will split a bill across, and splitting after the fact is administratively awkward. Deciding the approach before ordering, and having one person pay with reimbursement afterwards, avoids the negotiation at the end of the meal.
At a glance
| Tip base | The amount you enter, so use the subtotal for pre-tax tipping |
|---|---|
| Split | Even division across the number of people |
| Watch for | Service charges and automatic gratuities already on the bill |
| Transmitted | Nothing |
Frequently asked questions
Should I tip on the pre-tax or post-tax amount?
Pre-tax is conventionally correct. On a $100 subtotal with 8 percent tax, an 18 percent tip differs by about $1.44 between the two.
Do I tip on top of a service charge?
No. An automatic gratuity is a tip. Check the itemised lines, since terminal-suggested percentages are often calculated on a total that already includes it.
What is the quickest way to work out 18 percent?
Take 20 percent by doubling the tenth, then subtract a tenth of that. On $86.50 that is $17.30 minus $1.73, about $15.57.
How should we split unevenly?
Allocate individual items, then divide shared dishes, tax, and tip proportionally to each subtotal rather than evenly.
Read more
Everyday math — A 50 percent gain and a 50 percent loss leave you down 25 percent, and that is the least surprising thing here.