Three common percentage calculations, all in one place. Results update as you type.
Percentages describe a part of a whole out of 100, and they come up constantly in everyday life — discounts, tips, grades, statistics, taxes, growth rates. This free tool covers the three percentage calculations people search for most often, all on one page, so you never have to remember which formula applies to which situation.
Every result updates instantly as you type, with no sign-up and no data ever leaving your browser. Whether you're checking a sale price, grading a test, or comparing year-over-year numbers, the right calculation is right here.
Use this when you know a percentage and a total, and want to find the resulting amount — for example, "what is 20% of $150?" This is the calculation behind discounts, tips, and commission amounts. Simply enter the percentage and the total, and the result appears immediately.
Formula: result = (percentage ÷ 100) × total. For 20% of 150: (20 ÷ 100) × 150 = 30.
Use this when you have two numbers and want to know what percentage one is of the other — for example, "30 out of 150 is what percent?" This is useful for test scores, survey results, completion rates, and market share comparisons.
Formula: percentage = (part ÷ whole) × 100. For 30 out of 150: (30 ÷ 150) × 100 = 20%.
Use this to find how much something has grown or shrunk in percentage terms between two values — for example, going from 100 to 120 is a 20% increase, while going from 120 to 100 is a 16.67% decrease (not 20%, since the base changes direction). This is the calculation used for price changes, salary raises, weight change, and year-over-year business comparisons.
Formula: % change = ((new value − old value) ÷ old value) × 100. A positive result means an increase; a negative result means a decrease.
All percentage math comes back to one relationship: percentage = (part ÷ whole) × 100. Once you understand that, all three calculators above are really just different ways of rearranging that same equation to solve for a different missing piece — sometimes you know the percentage and need the part, sometimes you know the part and whole and need the percentage, and sometimes you're comparing two "wholes" to find the percentage of change between them.
A jacket costs $80 and is 25% off. What's the discount? (25 ÷ 100) × 80 = $20 off, making the sale price $60.
You answered 42 questions correctly out of 50. What percentage is that? (42 ÷ 50) × 100 = 84%.
Your salary went from $50,000 to $54,000. What's the percentage increase? ((54,000 − 50,000) ÷ 50,000) × 100 = 8%.
Because each percentage change is calculated against a different base value. Increasing 100 by 20% gives 120, but decreasing 120 by 20% gives 96, not 100 — the base amount changed in between.
Yes, all three calculators accept decimal values for both the percentage and the numbers involved.
Yes — if the new value is smaller than the old value, the percentage change calculator will show a negative percentage, correctly representing a decrease.
Docutoolbox