How to calculate a tip

A tip is a percent of the bill, usually 15%, 18% or 20%. Start with 10%, then build the tip you want in your head.

Start with 10%

To find 10% of a bill, move the decimal point one place left. 10% of $46.00 is $4.60. Every common tip can be built from this one number.

See it: pictures to draw with your child

Copy these onto paper or a whiteboard. A quick sketch makes the idea concrete before any written method.

percentamount0%$010%$4.6015%$6.9020%$9.20100%$46
From 10% ($4.60), build 15% and 20%.
15%100%6.946percentamount
A 15% tip is the shaded part of the bill.
Bill: $60With tip: $72
A 20% tip makes the total 120% of the bill.

Why tips are percents

In the US, restaurant servers earn much of their pay from tips. Using a percent means the tip grows with the bill, so a bigger meal gives a bigger tip.

Customs differ around the world. In many countries a service charge is already added, and tips are small or not expected. The maths is useful either way.

Working out an exact tip

For an exact answer, multiply the bill by the percent as a decimal. An 18% tip on $46 is 0.18 × 46 = $8.28. Then add it to the bill: $46 + $8.28 = $54.28.

Many people tip on the amount before tax. Others tip on the total. Either is fine, but agree which before you calculate.

Find the tip

Type the tip percent and the bill. Add the answer to the bill for the total.

Splitting the bill

To split a bill fairly, add the tip first, then divide by the number of people. A $60 bill with a 20% tip is $72. Shared by 4 people, each pays $18.

Dividing first works too: each person pays $15, plus 20% of $15, which is $3. The answer is the same $18, a nice check of the maths.

Rounding the tip

People often round to a friendly amount. If 15% of a bill is $6.90, they might leave $7. Rounding up a little is common and kind.

Estimating first also helps. A $38.75 bill is about $40, so a 20% tip is about $8. That quick check catches slips with the decimal point.

Turning tips into practice

Restaurants are a perfect place to practice. Let your child read the bill, find 10%, and build the tip before anyone touches a phone calculator.

At home, use takeaway menus. Choose a meal, add up the prices, then work out 15% and 20% tips. Children love being trusted with real money decisions.

A quick tip table

Bill10%15%18%20%
$20$2$3$3.60$4
$40$4$6$7.20$8
$60$6$9$10.80$12
$80$8$12$14.40$16
$100$10$15$18$20

Notice the patterns: every column grows steadily, and the 20% column is always double the 10% column. Ask your child to fill in a row for $50 before looking it up.

Quiz: tips

Find the tip on a bill. Type amounts like 6.90.

Where this fits: percentages step by step

  1. What is a percent
  2. Percent to fraction
  3. Fraction to percent
  4. Percent to decimal
  5. Decimal to percent
  6. Comparing fractions, decimals and percents
  7. Benchmark percents
  8. Percent mental math
  9. Over 100% and under 1%
  10. Percent of a number
  11. Finding the percent
  12. Finding the whole
  13. Percent change
  14. Percent increase and decrease
  15. Discounts and sale price
  16. Sales tax
  17. Tips (this page)
  18. Simple interest
  19. Markup, commission and percent error
  20. Percent word problems

What to say to your child

A short script for teaching it the first time. Pause after each line and let your child do the next step.

  1. “Our bill is $30. What is 10%?” ($3.)
  2. “What is 20%?” ($6.)
  3. “And 15%?” ($3 + $1.50 = $4.50.)
  4. “If we leave 20%, what do we pay in total?” ($36.)
  5. “Split between 3 of us?” ($12 each.)

More worked examples

Example 1: 15% of $40

10% is $4, 5% is $2, so $6.

Example 2: 20% of $55

10% is $5.50, so 20% is $11.

Example 3: 18% of $50

0.18 × 50 = $9.

Example 4: splitting

$80 bill, 15% tip: $92 total. 4 people pay $23 each.

Practice questions (answers below)

Ask these out loud or write them down. Check each answer, and ask “how did you get that?” for one or two.

  1. 10% of $30
  2. 20% of $30
  3. 15% of $30
  4. 15% of $60
  5. 20% of $45
  6. 18% of $100
  7. Total of $50 with a 20% tip
  8. $40 with 15% tip, split by 2
  9. Estimate 20% of $38.75
  10. Stretch: 25% of $36
Show the answers
  1. $3
  2. $6
  3. $4.50
  4. $9
  5. $9
  6. $18
  7. $60
  8. $23 each
  9. about $8
  10. $9

Common mistakes

Moving the point the wrong waySays 10% of $46 is $460.Fix: 10% is smaller: $4.60.
Forgetting to add the tipPays just the tip.Fix: the total is the bill plus the tip.
Splitting before tipping, then forgettingDivides the bill but leaves no tip.Fix: add the tip first, or tip on each share.

How to teach it at home

Menu maths

Order from a takeaway menu, then work out the tip.

Restaurant helper

Let your child find the tip when you eat out.

Tip chart

Make a chart of 15% and 20% tips for bills from $10 to $100.

By grade

More for each grade: Grade 7 math and the CBSE class 7 maths guide.

Worksheets and practice

Tax, tip and interest worksheet, page 1

Tax, tip and interest worksheet: printable PDF with an answer key. · Make a fresh test

Tax, tip and interest worksheet · Percent practice · percent calculator · fraction, decimal and percent converter · percentage quiz · percent levels · percent games · percentages for kids

Last reviewed

Questions parents ask

How do you calculate a 15% tip?

Find 10% of the bill, then add half of that. 15% of $40 is $4 + $2 = $6.

How do you calculate a 20% tip?

Find 10% and double it. 20% of $55 is $11.

Should you tip before or after tax?

Either. Many people tip on the amount before tax; agree on one before calculating.

How do you split a bill with a tip?

Add the tip to the bill, then divide by the number of people.

What grade learns tips?

Grade 7 under Common Core 7.RP.A.3.