Percentage Calculator

Calculate percentages instantly — find X% of Y, what percent X is of Y, or the percentage change between two numbers.

Reference table

Percentage	Answer	Formula Used	Step-by-Step
1	0.85	1% of 85 = 0.85	85 × 1 / 100 = 0.85
2	1.7	2% of 85 = 1.7	85 × 2 / 100 = 1.7
3	2.55	3% of 85 = 2.55	85 × 3 / 100 = 2.55
4	3.4	4% of 85 = 3.4	85 × 4 / 100 = 3.4
5	4.25	5% of 85 = 4.25	85 × 5 / 100 = 4.25
10	8.5	10% of 85 = 8.5	85 × 10 / 100 = 8.5
15	12.75	15% of 85 = 12.75	85 × 15 / 100 = 12.75
20	17	20% of 85 = 17	85 × 20 / 100 = 17
25	21.25	25% of 85 = 21.25	85 × 25 / 100 = 21.25
30	25.5	30% of 85 = 25.5	85 × 30 / 100 = 25.5
40	34	40% of 85 = 34	85 × 40 / 100 = 34
50	42.5	50% of 85 = 42.5	85 × 50 / 100 = 42.5
60	51	60% of 85 = 51	85 × 60 / 100 = 51
70	59.5	70% of 85 = 59.5	85 × 70 / 100 = 59.5
75	63.75	75% of 85 = 63.75	85 × 75 / 100 = 63.75

Percentage Tips

To find 10%, just move the decimal point one place to the left
To find 50%, simply divide the number by 2
To find 25%, divide by 4 or halve the 50% result
Percentage increase = (new - old) / old × 100

What Is a Percentage?

A percentage is a way of expressing a number as a fraction of 100. The word comes from the Latin 'per centum,' meaning 'by the hundred.' Percentages are used everywhere in daily life — from calculating discounts and tips to understanding interest rates, test scores, and statistics. When you see 25%, it means 25 out of every 100, or one quarter of the total. The concept makes it easy to compare proportions regardless of the actual quantities involved. For example, saying a product is '30% off' immediately communicates the savings without needing to know the original price.

How to Calculate Percentages

There are three fundamental percentage calculations. First, finding X% of Y: multiply Y by X and divide by 100. For example, 15% of 200 is (200 × 15) / 100 = 30. Second, finding what percent X is of Y: divide X by Y and multiply by 100. For example, 30 is what percent of 200? (30 / 200) × 100 = 15%. Third, percentage change: subtract the old value from the new value, divide by the old value, and multiply by 100. If a price goes from $80 to $100, the change is ((100 - 80) / 80) × 100 = 25% increase. Each formula is simply a rearrangement of the same basic relationship: Part = Percentage × Whole / 100.

Common Percentage Mistakes

Percentage points vs. percentages: Going from 10% to 15% is a 5 percentage point increase but a 50% increase
Order matters for change: A 50% increase followed by a 50% decrease does NOT return to the original value
Base confusion: '20% of 50' and '50% of 20' give the same result (10), but represent different scenarios
Compounding: Repeated percentage changes compound — 10% growth per year for 7 years roughly doubles the value
Rounding errors: Always use the full decimal in intermediate steps and only round the final answer
Negative percentages: A negative percentage change means a decrease, not an error

Real-World Percentage Uses

Shopping: Calculate discounts, sales tax, and final prices to make informed purchase decisions
Finance: Interest rates, returns on investment, inflation rates, and loan APRs are all expressed as percentages
Cooking: Scale recipes up or down by a percentage to serve more or fewer people
Grades: Convert raw scores (42 out of 50) to percentages (84%) for standardized comparison
Tipping: Calculate restaurant tips by finding 15-20% of the pre-tax bill
Statistics: Polls, surveys, and research results rely on percentages to convey findings clearly

Step-by-Step Examples

See how common percentage problems are solved

25% Discount on $80 Item

Discount = 80 × 25 / 100 = $20
Sale price = $80 - $20 = $60

You save $20, paying $60

Score 37 out of 45 on a Test

Percentage = (37 / 45) × 100
Percentage = 0.8222 × 100 = 82.2%

Your score is 82.2%

Frequently Asked Questions

How do I calculate a percentage of a number?

Multiply the number by the percentage and divide by 100. For example, 20% of 150 = 150 × 20 / 100 = 30.

How do I find what percentage one number is of another?

Divide the part by the whole and multiply by 100. For example, 45 is what percent of 200? (45 / 200) × 100 = 22.5%.

How do I calculate percentage change?

Subtract the old value from the new value, divide by the old value, and multiply by 100. Formula: ((New - Old) / Old) × 100.

What is the difference between percentage and percentage points?

If an interest rate goes from 5% to 8%, it increased by 3 percentage points but by 60% as a percentage change ((8-5)/5 × 100 = 60%).

How do I convert a fraction to a percentage?

Divide the numerator by the denominator and multiply by 100. For example, 3/8 = 0.375 × 100 = 37.5%.

How do I reverse a percentage to find the original value?

If you know the final value after a percentage increase/decrease, divide by (1 + rate/100) for increases or (1 - rate/100) for decreases. Example: $120 after a 20% increase means the original was 120 / 1.20 = $100.