Percent to Decimal Calculator
This percent to decimal calculator divides a percent by 100: 45% = 0.45 and 42.5% = 0.425. To turn a decimal back into a percent, multiply by 100.
Sources: OpenStax Prealgebra 2e Updated
Percent to Decimal
Decimal to Percent
How to convert a percent to a decimal
Percent means per hundred, so a percent is already a number of hundredths, as OpenStax Prealgebra puts it. To write it as a decimal:
- Drop the % sign: 42.5% becomes 42.5.
- Divide by 100, which moves the decimal point two places to the left: 42.5 ÷ 100 = 0.425.
- If the point runs out of digits, fill the gap with zeros: 4% = 0.04 and 0.5% = 0.005.
How to convert a decimal to a percent
- Multiply by 100, which moves the decimal point two places to the right: 0.06 × 100 = 6.
- Add the % sign: 6%.
The two boxes in the calculator work independently, so you can convert one way without clearing the other.
Percent to decimal chart
| Percent | Decimal | Percent | Decimal |
|---|---|---|---|
| 0.5% | 0.005 | 25% | 0.25 |
| 1% | 0.01 | 33.3% | 0.333 |
| 5% | 0.05 | 50% | 0.5 |
| 10% | 0.1 | 75% | 0.75 |
| 12.5% | 0.125 | 100% | 1 |
| 20% | 0.2 | 150% | 1.5 |
Why percents are turned into decimals
A decimal can go straight into a multiplication. To find 42.5% of $80, work out 80 × 0.425 = $34, not 80 × 42.5. The percentage calculator does this step and the others in a percent problem.
A percent can also be written as a fraction: 42.5% = 17/40, which the percent to fraction calculator simplifies for you. For a decimal that is already in hand, use the decimal to fraction calculator.
Rounding in the calculator
Results are rounded to 12 significant digits. That hides floating-point noise, such as 0.1 + 0.2 showing as 0.30000000000000004, while keeping plenty of precision. A blank or non-numeric entry gives an error message instead of a silent zero.
Questions about percents and decimals
How do you convert a percent to a decimal?
Divide by 100, which moves the decimal point two places to the left. 45% = 0.45, 7% = 0.07 and 150% = 1.5.
How do you convert a decimal to a percent?
Multiply by 100, which moves the decimal point two places to the right, and add the % sign. 0.06 = 6% and 1.25 = 125%.
What is 0.5% as a decimal?
0.005. Dividing 0.5 by 100 moves the point two places left, so two zeros come in front of the 5.
Sources
- OpenStax Prealgebra 2e, 6.1 Understand Percent — percent as per hundred, and converting between percents, decimals and fractions (checked October 16, 2026)