Fractions, decimals, and percentages describe the same amount
A fraction, a decimal, and a percentage are three ways to write one part of a whole. The notation changes; the value does not.
A fraction names a number of equal parts. A decimal writes those parts using place value. A percentage names the same amount out of 100.
To move from a fraction to a percentage, divide the numerator by the denominator and multiply by 100. To move from a decimal to a percentage, move the decimal point two places to the right — equivalently, multiply by 100.
Key idea
See the relationship
3/8=0.375=37.5%
Quick guide
How to use this calculator
Enter the known values using ordinary signed decimals.
Choose an interpretation or relationship when the calculator provides one.
Read the exact result, decimal preview, and any domain explanation.
Calculation method
Use the stated percentage or ratio relationship
percentage = numerator/denominator × 100%
The calculator keeps finite-decimal inputs as exact reduced fractions and rejects a zero reference or denominator whenever the requested relative quantity would be undefined.
Worked example
Worked interpretation
3/8 = 37.5%.
percentage = numerator/denominator × 100%
Supported inputs
Precision and limits
Input precision
Each value may contain up to 30 digits and 15 decimal places. Scientific notation, fractions typed with a slash, and thousands separators are not accepted.
Exactness
Finite decimals are converted to reduced rational numbers. Detected repeating digits appear in parentheses, while previews that exceed the display limit end with an ellipsis; the exact fraction remains available.
Lists and ratios
List-based tools accept 2–12 entries separated by commas, colons, semicolons, or new lines. Ratio parts must satisfy the positivity rules shown by the calculator.
