Percentage Calculator
Find what any percentage of a number equals, instantly.
Short answer: Calculate any percentage in one step: find what percent one number is of another, take a percent of a number, or work out the percent increase or decrease between two values. Type your numbers and the answer updates instantly — no buttons to press, no sign-up, nothing to install.
Last updated: October 13, 2026
How it works
Enter a percentage and the number it applies to. The answer and a plain-English sentence — “20% of 150 is 30” — update as you type, with no button press required. The math is the standard formula: result = percentage ÷ 100 × base number.
It works for discounts, tax, tips, grades, and growth figures alike — anything that is a share of a whole.
A worked example
The tool loads with a classic example already answered:
Try 15% of 86 for a tip calculation (12.9), or 8% of 250 for a quick tax estimate (20) — the result updates the moment either number changes.
Frequently asked questions
What is the formula for a percentage of a number?
Divide the percentage by 100 and multiply by the base: (percent ÷ 100) × number. So 20% of 150 is 0.2 × 150 = 30.
How do I calculate a discount price?
Find the discount amount with this calculator, then subtract it. A 20% discount on 150 is 30 off, so you pay 120. Equivalently, 80% of 150 gives the sale price directly.
How do I find a percentage increase?
Subtract the old value from the new one, divide by the old value, and multiply by 100. From 150 to 180: (180 − 150) ÷ 150 × 100 = 20% increase.
Why does the result show a dash?
One of the fields is empty or not a valid number. Fill in both the percentage and the base number and the answer appears immediately.
Can percentages be over 100?
Absolutely. 150% of 80 is 120 — percentages over 100 simply mean more than the whole base amount.
What is the difference between percent and percentage points?
Percent is relative; percentage points are absolute. A rate rising from 10% to 15% is up 5 percentage points, but up 50 percent relative to where it started.
How do I calculate a discount?
Multiply the original price by (1 − discount). A $80 jacket at 25% off: 80 × 0.75 = $60. The discount itself is 80 × 0.25 = $20.
How do I add a percentage to a number?
Multiply by (1 + the percentage as a decimal). Adding 8% tax to $50: 50 × 1.08 = $54.
The three percentage questions
Almost every percentage problem is one of three questions, each with its own formula. Once you recognize which one you are asking, the arithmetic is simple.
1. What is X% of Y?
Multiply: Y × X / 100. A 20% tip on a $150 bill is 150 × 20 / 100 = $30. This is also how you take a percentage off: a $80 jacket at 25% off costs 80 × (1 − 0.25) = $60.
2. X is what percent of Y?
Divide and scale: X / Y × 100. If you scored 30 out of 150, that is 30 / 150 × 100 = 20%. Useful for grades, completion rates, and "what share of my budget went to rent?" questions.
3. What is the percentage change from X to Y?
Take the difference relative to the starting point: (Y − X) / X × 100. Sales rising from $120k to $150k grew by (150 − 120) / 120 × 100 = 25%; falling from $150k to $120k is a −20% change. Note the asymmetry: a 25% rise followed by a 25% fall does not return to the start, because the second percentage applies to the larger number.
Percentage points versus percent
That distinction matters whenever the underlying quantity is itself a percentage: election polls, tax rates, and test scores. "Up 5%" on a 10% base means 10.5%, while "up 5 percentage points" means 15% — very different outcomes from nearly identical phrasing.
How do I calculate percent increase or decrease?
Subtract the old value from the new value, divide by the old value, then multiply by 100. If a price rises from $40 to $50, that’s (50 − 40) ÷ 40 × 100 = 25% increase.
If it falls from $50 to $40, it’s (40 − 50) ÷ 50 × 100 = −20% — note the decrease is 20%, not 25%, because the starting point changed. That asymmetry trips people up constantly: going up 25% and then down 25% does not return you to the start.
What percent is X of Y?
Divide X by Y and multiply by 100. If you scored 42 out of 50 on a test, that’s 42 ÷ 50 × 100 = 84%.
This is the same calculation behind grades, poll results, and completion rates — any time you need one number expressed as a share of another, this is the formula.
How do I convert a percentage to a decimal or fraction?
Divide by 100: 75% becomes 0.75, and 12.5% becomes 0.125. For fractions, put the percentage over 100 and simplify — 75% is 75/100, which reduces to 3/4.
Going the other way, multiply a decimal by 100: 0.06 is 6%. These conversions come up whenever a formula expects a decimal rate but the problem states a percentage.