You get the check. The subtotal says $80. Sales tax at 8% adds another $6.40, pushing the total to $86.40. Now you have to decide: do you tip on the $80, or on the $86.40?
Standard etiquette says the $80. The tip is compensation for service. The tax is a payment to the state. Your server does not receive any portion of the sales tax you pay, so including it in the tip base inflates the calculation without adding anything for the person who earned it.
The actual math on a real example
Here is that $80 meal worked out at 20%, both ways.
| Calculation basis | Tip base | 20% tip |
|---|---|---|
| Pre-tax (subtotal) | $80.00 | $16.00 |
| Post-tax (total) | $86.40 | $17.28 |
The difference is $1.28. On a $40 lunch, it would be around $0.64. This is not going to change your life either way, but knowing the baseline helps when you use a tip calculator and want to understand what the numbers mean.
Sales tax rates vary a lot by state and city. New York City diners pay a combined rate near 8.875%. Some states, like Oregon, have no sales tax at all, which makes the question moot. The gap between pre-tax and post-tax tipping shrinks as the tax rate drops and grows as it rises.
Do you tip on the total or subtotal?
This is the most common tipping question, and the answer is subtotal. Emily Post's guide on tipping, a reference that has been around since 1922, says the tip should be based on the bill before tax. The general consensus from hospitality industry sources lines up with that. Tipping on the post-tax amount is not wrong, exactly. Your server will not send it back. But the pre-tax figure is what the service actually cost, and that is the number the percentage is meant to apply to.
There is one situation where tipping on the total is actually fine: when the total is an easy number to work with and the pre-tax subtotal is not. If your bill comes to exactly $90 after tax and you want to leave 20%, it is perfectly reasonable to tip $18 rather than hunting down the subtotal. The spirit of the tip matters more than the decimal point.
How much to tip at different percentages
Using the same $80 pre-tax example, here is what each common percentage works out to.
| Tip percentage | Tip on $80 pre-tax | Total paid |
|---|---|---|
| 15% | $12.00 | $98.40 |
| 18% | $14.40 | $100.80 |
| 20% | $16.00 | $102.40 |
| 25% | $20.00 | $106.40 |
Total paid includes the $6.40 tax (8% on $80) in each row.
Is 20 percent a good tip?
It is the current standard for good service at a sit-down restaurant in the United States. That was not always true. For most of the twentieth century, 15% was the norm. The shift to 20% as the baseline happened gradually over the past couple of decades, partly because the real wages of tipped workers have not kept pace with costs, and partly because touch-screen payment terminals now default to 20, 25, or 30% as their first three options. Whether that nudge is fair or pushy depends on who you ask, but 20% is now what servers in most American cities expect for competent service.
Below 15% reads as a comment on the service, not just a smaller tip. Above 25% is appropriate when something genuinely went right: attentive refills without being asked, good menu knowledge, a problem handled gracefully.
How to calculate a 15 percent tip quickly
Move the decimal one place to the left to get 10%, then add half of that to get 15%. On an $80 bill: 10% is $8.00, half of that is $4.00, so 15% is $12.00. It takes about four seconds once you know the trick. For 20%, just double the 10% figure: $8.00 times two is $16.00.
If you want the math done for you, see the how much should you tip guide or plug numbers into the calculator at the top of the page. The calculator defaults to the pre-tax subtotal field for exactly this reason.
How much do you tip for a $100 bill?
On a $100 pre-tax bill, 20% is $20. That one is easy. If your bill is $100 after tax, back out the tax first to find the subtotal, then tip on that. In a city with 8% sales tax, the pre-tax subtotal on a $100 post-tax bill is roughly $92.59, and 20% of that is about $18.52. In practice, most people in that situation round to $18 or $19 and call it done. The point is not to obsess over cents. The point is to be fair to the person who served you.
When the tax-or-pretax question does not apply
At takeout windows and coffee counters, the tip prompt on screen is usually applied to the total (including tax) because the software does not break out a separate subtotal. The amounts are smaller, so the difference is trivial. For delivery orders placed through apps, the platform often calculates the suggested tip on the pre-tax subtotal, but this varies by app.
At bars, the convention is to tip per drink (usually $1 to $2 per drink, or around 20% of the tab) rather than on the food total. If you are running a tab, tip at the end based on the drink subtotal.
For more on how tipping norms vary by setting, the tipping etiquette guide for the United States covers restaurants, bars, delivery, and a few of the genuinely awkward situations most people just guess at.
The short version
Tip on the pre-tax subtotal. The math is cleaner, the logic is sound, and it is what most etiquette sources recommend. On the average restaurant bill, the difference between pre-tax and post-tax tipping is less than $1.50. Either approach is fine for your server. The pre-tax method is just more defensible if anyone asks.
Frequently asked questions
Do you tip on the total or subtotal?
Standard etiquette says to tip on the pre-tax subtotal. The tip compensates the server for their work. Sales tax goes to the government, not to the person who brought your food, so there is no real reason to include it in the tip calculation.
How much do you tip for a $100 bill?
On a $100 pre-tax bill, a 20% tip is $20.00 and a 15% tip is $15.00. If $100 is the post-tax total, back out the sales tax first to find the subtotal, then tip on that. In most U.S. cities, the pre-tax subtotal on a $100 bill after tax lands somewhere between $90 and $95 depending on the local tax rate.
Is 20 percent a good tip?
Yes. It is the current baseline for good service at a sit-down restaurant in the United States. Fifteen percent is still reasonable for adequate service. Going above 20% is a solid signal that something genuinely impressed you, and servers notice.
How do you calculate a 15 percent tip?
Multiply the pre-tax subtotal by 0.15. Shortcut: move the decimal one place left to get 10% of the bill, then add half of that to get 15%. On an $80 bill, 10% is $8.00 and half of that is $4.00, so 15% is $12.00.