Math Solver Free

Percentage Calculator

Find X% of Y, what percent X is of Y, and percentage change โ€” instantly and free.

20% of 150 = 30

Step 1: Convert the percent to a decimal: 20 รท 100 = 0.2

Step 2: Multiply by the value: 0.2 ร— 150 = 30

โ† Back to All Calculators

How to Calculate Percentages

A percentage is simply a fraction out of 100 โ€” the word itself comes from the Latin per centum, meaning โ€œby the hundred.โ€ Percentages show up everywhere: store discounts, tips, exam grades, interest rates, and statistics. There are three calculations most people need, and this tool handles all of them.

The Three Percentage Formulas

  • X% of Y: (X รท 100) ร— Y. Example: 20% of 150 = 0.20 ร— 150 = 30.
  • X as a percent of Y: (X รท Y) ร— 100. Example: 30 is (30 รท 150) ร— 100 = 20% of 150.
  • Percentage change: ((New โˆ’ Old) รท Old) ร— 100. A price rising from $100 to $125 is a 25% increase.

Everyday Uses

Shopping sales (โ€œ30% offโ€), restaurant tips, grade calculations, and salary raises all come down to these same three formulas. Once you see the pattern, you can estimate most percentages mentally: 10% of anything is just moving the decimal point one place left.

Percent vs. Percentage Points

One common trap: if an interest rate rises from 5% to 7%, that is a 2 percentage point increase โ€” but a 40% percent increase relative to the original 5%. News headlines mix these up constantly. When comparing two percentages, always check which one the writer means.

Need quick arithmetic for the steps above? Try our four-function calculator.

Frequently Asked Questions

How do I calculate 20% of 150?

Multiply 150 by 0.20 (which is 20 รท 100) to get 30. In general, X% of Y equals (X รท 100) ร— Y โ€” the calculator above does this instantly.

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

Divide the first number by the second and multiply by 100. For example, 30 as a percentage of 150 is (30 รท 150) ร— 100 = 20%.

How do I calculate percentage increase or decrease?

Subtract the old value from the new value, divide by the old value, then multiply by 100. A positive result is an increase; a negative result is a decrease.

Is this percentage calculator free?

Yes โ€” every tool on Math Solver Free is free with no sign-up, and all calculations run in your browser.