Math
Fraction to Decimal Calculator
Enter a numerator and a denominator to see the decimal, the percentage and the simplest form.
The formula
decimal = numerator ÷ denominator
simplest form = both parts ÷ their greatest common divisor
Worked example
Three eighths of an inch, in decimal
- 3 ÷ 8 = 0.375
- 0.375 × 100 = 37.5%
- 3/8 is already in its simplest form
Where this goes wrong
Rounding a repeating decimal too early
One third is 0.333… forever, not 0.33. Round it before you multiply and the error grows with everything you do afterwards — a third of 300 becomes 99 rather than 100. Keep the fraction as long as you can and round only the final answer.
Questions
- How do I simplify a fraction?
- Divide the top and the bottom by their greatest common divisor. For 18/24 that divisor is 6, giving 3/4. Dividing by anything smaller reduces the fraction without finishing the job.
- What is an improper fraction?
- One where the numerator is larger than the denominator, such as 11/4. It is perfectly valid, and can also be written as the mixed number 2 3/4.
- Why do some fractions give endless decimals?
- A fraction terminates only when its simplified denominator has no prime factors other than 2 and 5. That is why 3/8 gives an exact 0.375 while 1/3 repeats forever.