How to calculate a tip: 15%, 18% and 20% in your head
Find 10% by moving the decimal point, then build 15%, 18% or 20% from it. Worked examples on a $64 bill, a one-step multiplier for the total, and how to round the tip.
Start with 10%: move the decimal one place left ($64.00 → $6.40). Half of that is 5% ($3.20). Add them for 15% ($9.60), or double 10% for 20% ($12.80). For the total in one step, multiply the bill by 1.15 or 1.20.
On this page
You don’t need a phone to work out a tip. Every common tip percentage can be built from 10%, which takes no arithmetic at all.
Step 1: find 10%
Move the decimal point one place to the left. On a $64.00 bill, 10% is $6.40.
Step 2: build the tip you want
- 15%: 10% plus half of it. $6.40 + $3.20 = $9.60.
- 20%: double 10%. $6.40 × 2 = $12.80.
- 18%: 20% minus 2%. $12.80 − $1.28 = $11.52.
- 25%: 20% plus 5%. $12.80 + $3.20 = $16.00.
Check the 20% tip and total:
Try it: 20% tip on $64
Open in calculatorThe total in one step
Multiply the bill by 1 plus the tip as a decimal:
total = bill × (1 + tip % ÷ 100)
Where a 15% tip uses 1.15
$64 × 1.15 = $73.60.
Try it: 15% tip on $64
Open in calculatorAn awkward bill
For $47.30: 10% is $4.73, so 20% is $9.46 and the total is $56.76. If that’s fiddly, round the bill first. 20% of $47 is $9.40, close enough, and many people then round the total up to a whole dollar.
Try it: 20% tip on $47.30
Open in calculatorHow much to tip
Customs vary by country, by type of service, and over time. In the US, 15% to 20% is a common range for table service at restaurants. In many other countries, service is included in the price or tips are smaller. If the bill already shows a service charge, read service charge vs tip before adding more.
Related
Questions
How do I work out an 18% tip in my head?
Take 20% and subtract 2%. On $64, 20% is $12.80 and 2% is $1.28 (a fifth of 10%), so 18% is $11.52. Or just round up to the nearest dollar from 15% and 20%.
Should I tip on the total with tax or the subtotal?
Tipping on the pre-tax subtotal is common, and the difference is usually small. Our guide on tipping before or after tax shows how much it changes at typical tax rates.
The calculator links in this guide are checked against the PercentSwift calculator every time the site is built. How we calculate explains the rounding rules. If you spot a mistake, email hello@percentswift.com.
