You've just finished a great meal and the check arrives. Your phone is buried in your bag, and you want to tip fairly without making everyone wait while you tap at an app. Good news: tip math is one of the easiest percentage calculations you can do in your head once you know a few shortcuts.
The 10% Foundation
Everything in tip math starts with 10%. To find 10% of any number, simply move the decimal point one place to the left.
- $42.80 -- 10% = $4.28
- $67.00 -- 10% = $6.70
- $113.50 -- 10% = $11.35
Once you have the 10% figure, every other standard tip is just addition or a small adjustment.
Calculating a 20% Tip
A 20% tip is simply 10% doubled. Find 10%, then multiply by two.
- Bill: $55.00 -- 10% = $5.50 -- 20% = $11.00
- Bill: $38.00 -- 10% = $3.80 -- 20% = $7.60
This is the most popular tipping percentage in the US today, and it's the easiest to calculate in your head.
Calculating a 15% Tip
For 15%, find 10%, then find half of that (which is 5%), and add them together.
- Bill: $40.00 -- 10% = $4.00 -- 5% = $2.00 -- 15% = $6.00
- Bill: $60.00 -- 10% = $6.00 -- 5% = $3.00 -- 15% = $9.00
Calculating an 18% Tip
18% feels awkward but it's just 20% minus 10% of the tip itself. Or more practically: find 20%, then subtract roughly 1/10th of that amount.
- Bill: $50.00 -- 20% = $10.00 -- 10% of $10 = $1.00 -- 18% is about $9.00
- Bill: $80.00 -- 20% = $16.00 -- 10% of $16 = $1.60 -- 18% is about $14.40
The Round Up to Make It Easy Method
If the bill is $43.70, round up to $44 or even $45 before doing your math. Nobody at the table will notice the difference, and you'll get a cleaner number to work with. A slightly more generous tip on a rounded number is always better than a confusing exact calculation.
A Quick Reference Table
| Bill | 15% Tip | 18% Tip | 20% Tip |
|---|---|---|---|
| $20 | $3.00 | $3.60 | $4.00 |
| $35 | $5.25 | $6.30 | $7.00 |
| $50 | $7.50 | $9.00 | $10.00 |
| $75 | $11.25 | $13.50 | $15.00 |
| $100 | $15.00 | $18.00 | $20.00 |
| $150 | $22.50 | $27.00 | $30.00 |
Should You Tip on the Pre-Tax or Post-Tax Amount?
Technically, tipping on the pre-tax subtotal is the traditional approach -- you're rewarding service, not compensating for government revenue. In practice, most people tip on the final total and it makes almost no difference on an average restaurant bill. On a $60 tab with 8% tax, the difference between tipping on $60 vs $64.80 is about $1 at 20%. Do what feels right to you.
When You Want to Go Above 20%
For truly exceptional service, or when supporting a smaller local restaurant, 25% is easy: that's 20% plus half of the 10% amount.
- Bill: $60 -- 20% = $12 -- 10% = $6 -- half of that = $3 -- 25% = $15
Mental tip math gets faster with practice. After a few dinners using these shortcuts, it'll feel completely natural. Prefer to skip the mental math entirely? Our Tip Calculator handles any bill size, any percentage, and splits among any number of people instantly.