Percentage Calculator
Calculate percentages, percent of a number, and percentage changes fast.
Find what a percentage of a number equals - e.g. 20% of 150.
A percentage calculator - useful as a general percentage finder, percent finder, or percent calculator for any percent-part-whole problem - handles the three questions people actually ask about percentages: what a percentage of a number equals, what percentage one number is of another, and how much something has increased or decreased. Percentages express a number as a fraction of 100, making it easier to compare proportions, discounts, grades, and statistics across very different scales.
Pick the mode that matches your question, enter the two known values, and the calculator returns the missing one instantly - along with a plain-English sentence explaining what the result means, not just a bare number.
Which Percentage Calculator Should I Use?
Use this when you know a percentage and a total, and need the actual amount it represents - a discount amount, a tip, a tax amount, or a share of a total.
"What is 20% of 150?" -> 30
Use this when you know two amounts and need to express one as a percentage of the other - a test score, a completion rate, or a budget category share.
"30 is what % of 200?" -> 15%
Use this when you have a before-and-after value and need to know how much it grew or shrank - a price change, a salary change, or business growth.
"From 50 to 75" -> +50%
Understanding Percentages
A percentage is just a fraction of 200 expressed out of 100. Here's what a few common percentages of 200 look like:
150% of 200 is larger than 200 itself - a percentage over 100% simply means "more than the whole."
Everyday Percentage Examples
A $80 jacket marked 25% off saves $20, bringing the price to $60 - the same "% of a number" math as any storefront discount sign.
Scoring 42 out of 50 on a test is the "X is what % of Y" question: 42 is what % of 50 -> 84%, the number that actually appears on the report card.
A raise from $60,000 to $66,000 a year is a percentage change of +10% - the same calculation used for any before-and-after comparison.
A store discounting a $250 item by 15% takes off 15% of 250 = $37.50, leaving a $212.50 sale price.
Revenue growing from $2M to $2.5M year over year is a 25% increase - the metric investors and reports quote as "growth rate."
Leaving an 18% tip on a $64 restaurant bill is 18% of 64 = $11.52 - the exact "% of a number" calculation, just with a different label.
Percentage Change vs. Percentage Difference
Percentage change compares a starting value to an ending value and always uses the starting value as the base - it's directional, so going from 50 to 100 is a +100% change, but going back from 100 to 50 is only a -50% change, even though the two values are the same pair.
Percentage difference is typically used when neither value is clearly the "before" or "after" - it measures how far apart two values are relative to their average, so it gives the same result regardless of which number you list first. The two terms get mixed up constantly because they both produce a percentage from two numbers, but they answer different questions.
Percentage vs. Percentage Points
If an interest rate rises from 20% to 25%, that's a 5 percentage point increase - the raw arithmetic difference between the two percentages. But it's also a 25% relative increase (5 divided by the original 20, times 100). Both numbers are correct; they just answer different questions, and news headlines often blur the two.
Common Percentage Mistakes
"30 is what % of 200" and "200 is what % of 30" are very different questions (15% vs. 667%) - the order of part and whole matters, and swapping them is the single most common percentage error.
A 20% increase followed by a 20% decrease does not return to the original value: 100 -> 120 (+20%) -> 96 (-20% of 120, not of 100) - each percentage change applies to a different base.
A percentage over 100% is completely valid - it simply means the part is larger than the original whole, common in growth figures like "sales are up 150% year over year."
Percentage change is undefined when the starting value is zero, since it requires dividing by the original amount - going from 0 to any positive number is not "infinite percent," it just has no defined percentage change.
Where Percentages Are Used
Discounts, sale prices, and cashback percentages.
Test scores, grade weighting, and attendance rates.
Interest rates, loan APRs, and investment returns.
Revenue growth, margins, and market share.
Survey results, probabilities, and data breakdowns.
Budgeting shares, savings rates, and salary changes.
Popular Scenarios & Specific Calculations
How to Use the Percentage Calculator
- Open the Percentage Calculator and enter the values requested in the input fields.
- Check the units, percentages, dates, or time periods before reading the answer.
- Review the instant result and adjust any value to compare another scenario.
- Use the formula, example, and FAQs below to understand how the percentage calculator works.
Frequently Asked Questions
How do I find what a percentage of a number is?
Divide the percentage by 100 and multiply by the number - for example, 20% of 150 is (20 / 100) x 150 = 30.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100 - for example, 30 is what percent of 200 is (30 / 200) x 100 = 15%.
How do I calculate percentage increase or decrease between two numbers?
Subtract the starting value from the ending value, divide by the starting value, then multiply by 100 - a positive result is a percentage increase, a negative result is a percentage decrease.
What is the difference between percentage change and percentage difference?
Percentage change is directional and always uses the starting value as its base, so going from 50 to 100 is +100% but going from 100 to 50 is only -50%. Percentage difference typically compares two values with neither treated as "before" or "after," so it gives the same result regardless of order.
What is the difference between a percentage and a percentage point?
A percentage point is the raw arithmetic difference between two percentages - a rate moving from 20% to 25% is a 5 percentage point increase. Expressed as a percentage, that same move is a 25% relative increase (5 divided by 20). Both are correct; they just measure different things.
Can percentages be greater than 100%?
Yes. A percentage greater than 100% simply means the part is larger than the whole it's being compared to - common in growth figures, like sales that are up 150% year over year.
Why can't I calculate a percentage change from zero?
Percentage change divides by the starting value, so a starting value of zero makes the calculation undefined - there is no original amount to measure the change against.
How do I calculate a percentage of a percentage?
Convert both percentages to decimals and multiply them - for example, 20% of 50% is 0.20 x 0.50 = 0.10, or 10%.
If a value increases by 20% and then decreases by 20%, does it return to the original number?
No. The increase and decrease apply to different bases: 100 grows to 120 (+20%), but 20% of 120 is 24, not 20, so it drops back to 96 - not the original 100.
How do I reverse a percentage to find the original number?
Divide the known part by the percentage as a decimal - for example, if 20% of a number is 30, the original number is 30 / 0.20 = 150.
Related Calculators
Percentage Increase Calculator
Calculate the percentage increase or decrease from an old value to a new value, the new value after an increase, or the original value, with steps.
Discount Calculator
Calculate sale prices after percentage discounts.
Sales Tax Calculator
Calculate state and local sales tax totals.
Tip Calculator
Split restaurant bills and compute tip percentages per person easily.
Last updated: September 29, 2026.