Percent to Decimal Calculator
Convert any percentage to a decimal instantly, plus its simplified fraction, per mille, and basis points
By Waqar Mushtaq · Last updated:
This percent to decimal calculator converts any percentage into its decimal form instantly — the number you actually need to type into a spreadsheet formula, a finance equation, or a probability problem. Enter a percentage and you get the exact decimal (with no floating-point noise like 0.33299999999999996), the simplified fraction, and the same value in per mille (‰) and basis points (bps). Negative percentages and percentages over 100% work the same way.
How to convert a percent to a decimal
O(1) calculationThe % sign stands for the number 0.01, so 45% means 45 × 0.01
"Percent" means "per hundred", and the % symbol is simply shorthand for the number 0.01. Converting a percent to a decimal therefore means dividing by 100 and dropping the % sign — the shortcut is to move the decimal point two places to the left.
Examples:
45% = 45 ÷ 100 = 0.457.5% = 7.5 ÷ 100 = 0.0750.5% = 0.5 ÷ 100 = 0.005— note the extra zero after the decimal point125% = 125 ÷ 100 = 1.25— percentages over 100% give decimals over 1-20% = -0.2
To a fraction: write the percent over 100 and simplify. 12.5% = 12.5/100 = 125/1000 = 1/8.
Per mille and basis points are the same idea with a different base: per mille is parts per thousand (1% = 10‰), and a basis point is one hundredth of a percent (1% = 100 bps), the unit lenders and bond markets use for small rate changes.
To go the other way, use the Decimal to Percent Calculator.
Use Cases
Spreadsheet and finance formulas
Interest, tax, and growth formulas expect rates as decimals: a 6.5% rate is entered as 0.065, and a 7% sales tax on $40 is 40 × 0.07 = $2.80.
Probability and statistics
Probabilities are written as decimals between 0 and 1, so a 35% chance of rain is a probability of 0.35.
Discounts and markups
A 30% discount leaves you paying 1 − 0.30 = 0.70 of the price; a 15% markup multiplies the cost by 1.15.
Reading rate changes in basis points
A quarter-point rate cut is 0.25% = 0.0025 = 25 basis points — the equivalents table shows all three forms at once.
Frequently Asked Questions
How do I convert a percent to a decimal by hand?
Divide by 100 — or move the decimal point two places to the left, adding zeros if you run out of digits. 8% becomes 0.08 and 0.3% becomes 0.003.
What is 100% as a decimal?
1. One hundred percent is the whole amount, so 100 ÷ 100 = 1. Anything over 100% gives a decimal greater than 1: 250% = 2.5.
Why does my calculator show 0.33299999999999996 for 33.3%?
Computers store numbers in binary, and most decimals (like 0.333) can't be represented exactly, so a straight division leaves a tiny error. This calculator rounds the result to exactly two more decimal places than your input, which is all a divide-by-100 can ever need, so you get the true answer 0.333.
How do I convert a percent to a fraction?
Put the percent over 100 and simplify. 40% = 40/100 = 2/5. If the percent has decimals, multiply the top and bottom by 10 until it is a whole number first: 2.5% = 2.5/100 = 25/1000 = 1/40.
Can a percentage be negative?
Yes — negative percentages describe decreases or losses (a -12% return) and convert the same way: -12% = -0.12.
Methodology
The formula above is implemented as a standalone module covered by unit tests, so its worked examples are re-checked on every change to the site. It is verified against the authoritative sources listed below.
Maintained by Waqar Mushtaq. Spotted a result that looks wrong? Report it and it becomes a failing test.