You’re looking at the check, the card reader is waiting, and your mind goes blank. What’s 18% of $63.40 again? We’ve all frozen there. The good news is that working out a tip is easier than the panic makes it feel, and once you know the trick you’ll never reach for your phone again.
The quick answer
To calculate a tip, multiply the bill by the tip percentage written as a decimal. So a 20% tip on a $50 bill is:
$50 × 0.20 = $10, which makes your total $60.
That’s the whole formula. Everything below is just faster ways to do it and the small stuff people argue about.
The 10% trick that does most of the work
Here’s the shortcut that makes you look like you’re good at math. Finding 10% of any number is simple — you just move the decimal point one spot to the left.
- 10% of $50 is $5.
- 10% of $63.40 is $6.34.
From there:
- Want 20%? Double the 10%. ($6.34 becomes about $12.68.)
- Want 15%? Take the 10%, then add half of it. ($6.34 plus $3.17 is roughly $9.50.)
- Want 18%? Land somewhere between the 15% and 20% numbers. Close is fine — nobody’s auditing you.
Notice you never actually multiplied by a weird decimal. You moved a decimal point and did one bit of easy addition. That’s the entire skill.
Common tips at a glance
If you’d rather just read it off a chart, here’s what the usual percentages come to on a few round bills.
| Bill | 15% | 18% | 20% | 25% |
|---|---|---|---|---|
| $20 | $3.00 | $3.60 | $4.00 | $5.00 |
| $40 | $6.00 | $7.20 | $8.00 | $10.00 |
| $60 | $9.00 | $10.80 | $12.00 | $15.00 |
| $80 | $12.00 | $14.40 | $16.00 | $20.00 |
| $100 | $15.00 | $18.00 | $20.00 | $25.00 |
For anything in between, round to the nearest row and adjust. A $58 bill behaves almost exactly like the $60 line.
How to calculate a tip without a calculator
You already have everything you need: the 10% trick above. Round the bill to a friendly number first, then do the mental math on that. A $47.80 check becomes “$48,” 10% of that is about $4.80, and a 20% tip is roughly $9.60. Rounding up a few cents also quietly nudges the tip in the server’s favor, which is a nice thing to do anyway.
If mental math genuinely isn’t your thing, that’s fine too — that’s exactly what our tip calculator is for. Punch in the bill, pick a percentage, and it hands you the tip and the new total instantly.
Do you tip on the pre-tax or post-tax amount?
Technically, you only owe a tip on the cost of the food and service, not the sales tax. Calculating on the pre-tax subtotal is completely correct and common. That said, plenty of people just tip on the final total because it’s one less number to hunt for, and the difference is usually small — a dollar or two. Do whichever feels right to you; both are normal.
Splitting the tip between people
Group dinners add one more step, but it’s a small one. Work out the tip on the full bill first, add it to the total, then divide by the number of people. Splitting first and tipping second can leave the table a little short, so total-then-split is the safer order. If you’d rather skip the arithmetic entirely, the calculator has a split field built in — set the number of people and it gives you each person’s share, tip included.
Frequently asked questions
Is 20% a good tip?
Yes. In the US, 20% is the standard for good sit-down restaurant service, and it’s an easy number to work out. Many people start at 18% and move up or down based on how the service went.
What’s the easiest way to figure out a 20% tip?
Find 10% by moving the decimal one place left, then double it. On a $45 bill, 10% is $4.50, so 20% is $9.
Should I tip on tax?
You don’t have to — the tip is really for the service, not the government’s cut. Tipping on the pre-tax subtotal is perfectly acceptable, though tipping on the total is common and only costs a little more.
How do I calculate a 15% tip quickly?
Take 10% of the bill, then add half of that number. On $60, that’s $6 plus $3, so $9.
Still doing the math the slow way? Try the free tip calculator — it handles the percentage, the tax, and the split for you.
For tipping in every other situation, see our complete US tipping guide.