Percentage cheat sheet: tip amounts and fraction to decimal to percent

A 20% tip on an $85 bill is $17.00, so the total is $102.00. To convert a fraction to a percent, divide the top by the bottom and multiply by 100: 3/8 is 0.375, or 37.5%. This page has a tip table for common bills and a fraction chart for everyday use.

Tip amounts are examples, not advice on what to leave. Customs vary by place and service.

How do you calculate a tip?

Tip = bill x tip percent / 100. Total = bill + tip. The tables here were generated with the same logic as Mathify's Tip Calculator by the script scripts/content-data/percent-tip-fraction-cheatsheet.ts.

A quick mental method: find 10% by moving the decimal point one place left, then add or double. On an $85 bill, 10% is $8.50, 5% is $4.25 (half of that), 15% is $12.75 (10% plus 5%) and 20% is $17.00 (10% doubled).

What is the tip on common bill amounts?

Assumptions: the percentage is applied to the pre-tip bill amount you enter, with no rounding, and amounts are in dollars. Each entry shows the tip and the bill plus tip.

$20.00 bill: 10% tip $2.00 (total $22.00) | 15% tip $3.00 (total $23.00) | 18% tip $3.60 (total $23.60) | 20% tip $4.00 (total $24.00) | 25% tip $5.00 (total $25.00)
$40.00 bill: 10% tip $4.00 (total $44.00) | 15% tip $6.00 (total $46.00) | 18% tip $7.20 (total $47.20) | 20% tip $8.00 (total $48.00) | 25% tip $10.00 (total $50.00)
$60.00 bill: 10% tip $6.00 (total $66.00) | 15% tip $9.00 (total $69.00) | 18% tip $10.80 (total $70.80) | 20% tip $12.00 (total $72.00) | 25% tip $15.00 (total $75.00)
$85.00 bill: 10% tip $8.50 (total $93.50) | 15% tip $12.75 (total $97.75) | 18% tip $15.30 (total $100.30) | 20% tip $17.00 (total $102.00) | 25% tip $21.25 (total $106.25)
$100.00 bill: 10% tip $10.00 (total $110.00) | 15% tip $15.00 (total $115.00) | 18% tip $18.00 (total $118.00) | 20% tip $20.00 (total $120.00) | 25% tip $25.00 (total $125.00)
$150.00 bill: 10% tip $15.00 (total $165.00) | 15% tip $22.50 (total $172.50) | 18% tip $27.00 (total $177.00) | 20% tip $30.00 (total $180.00) | 25% tip $37.50 (total $187.50)

Worked example: splitting an $85 bill four ways with an 18% tip

Tip: $85 x 0.18 = $15.30.
Total with tip: $100.30.
Per person: $25.08, of which $3.82 is each person's share of the tip.

The Bill Split Calculator handles uneven shares and extra items.

How do you convert fractions to decimals and percents?

Divide the numerator by the denominator for the decimal, then multiply by 100 for the percent. Repeating decimals are rounded; the marker "(repeating)" shows the value does not end. For the terminating fractions, the generating script also converted each percent back to a reduced fraction and confirmed the original.

Assumptions: decimals of repeating fractions are rounded to four places and percents to two places.

1/2: 0.5 | 50%
1/3: 0.3333 (repeating) | 33.33% (rounded)
2/3: 0.6667 (repeating) | 66.67% (rounded)
1/4: 0.25 | 25%
3/4: 0.75 | 75%
1/5: 0.2 | 20%
2/5: 0.4 | 40%
3/5: 0.6 | 60%
4/5: 0.8 | 80%
1/6: 0.1667 (repeating) | 16.67% (rounded)
5/6: 0.8333 (repeating) | 83.33% (rounded)
1/8: 0.125 | 12.5%
3/8: 0.375 | 37.5%
5/8: 0.625 | 62.5%
7/8: 0.875 | 87.5%
1/10: 0.1 | 10%
1/12: 0.0833 (repeating) | 8.33% (rounded)
1/16: 0.0625 | 6.25%
1/20: 0.05 | 5%
1/25: 0.04 | 4%

Use the Percent Converter for any other value and the Fraction Calculator to add, subtract, multiply or divide fractions.

How do you find a percentage of a number?

Multiply the number by the percent and divide by 100. A few examples:

15% of 240 = 36
20% of 85 = 17
12.5% of 64 = 8
35% of 180 = 63
7% of 450 = 31.5

For more types of percentage problems, use the Percentage Calculator.

How do you calculate percent change?

Percent change = (new - old) / old x 100. The base is always the old value.

From 80 to 120: (120 - 80) / 80 x 100 = 50% increase.
From 120 to 80: (80 - 120) / 120 x 100 = -33.33%, a decrease of one third.

This asymmetry is why a 25% increase followed by a 25% decrease does not return to the start. A 25% rise on 80 gives 100. A drop from 100 back to 80 is 20%, not 25%.

Common mistakes

Calculating a tip on a bill that already includes a service charge.
Using the wrong base for percent change (the new value instead of the old one).
Treating 33.33% as exactly one third; it is rounded.
Adding percentages that apply to different bases.
Entering 20 instead of 0.20 in tools that expect a decimal.

Key takeaways

Tip = bill x percent / 100; total = bill plus tip.
10% is the easiest anchor for mental math.
Fractions convert by dividing; some repeat forever.
Percent change always uses the old value as the base.

FAQ

How much is a 20% tip on $85?

$17.00, making the total $102.00.

What is 3/8 as a percent?

37.5%. As a decimal it is 0.375.

Is 1/3 equal to 33%?

No. One third is 0.3333... repeating, or about 33.33%. Using 33% is an approximation.

How do I calculate a tip without a calculator?

Find 10% by shifting the decimal, then add half of it for 15% or double it for 20%.

How do I turn a percent into a fraction?

Write it over 100 and reduce. 25% is 25/100, which reduces to 1/4.

Percentage cheat sheet: tip amounts and fraction to decimal to percent