Fraction to Decimal Conversion Tricks

Converting between fractions, decimals, and percentages is a core math skill. With a few memorized conversions and simple techniques, you can handle any conversion mentally.

Must-know conversions

1/2 = 0.5 = 50%. 1/4 = 0.25 = 25%. 1/3 = 0.333... = 33.3%. 1/5 = 0.2 = 20%. 1/6 = 0.1666... = 16.7%. 1/8 = 0.125 = 12.5%. 1/10 = 0.1 = 10%. 1/12 = 0.0833... = 8.3%.

Denominators that are powers of 10

If the denominator is 10, 100, or 1000, the conversion is trivial. 7/10 = 0.7. 23/100 = 0.23. 5/1000 = 0.005. For percentages, multiply by 100: 7/10 = 70%.

Denominators that divide into 100

If the denominator evenly divides 100, multiply both parts by the factor that makes the denominator 100. 3/4 → multiply by 25 → 75/100 = 0.75 = 75%. 3/20 → multiply by 5 → 15/100 = 0.15 = 15%.

Long division for any fraction

Divide the numerator by the denominator. 5/8: 5.000 ÷ 8. 8 goes into 50 six times (48), remainder 2. Bring down 0: 20. 8 goes into 20 two times (16), remainder 4. 40 ÷ 8 = 5. Result: 0.625.

Spotting repeating decimals

If the denominator has only factors of 2 and 5, the decimal terminates. Otherwise, it repeats. 1/3 = 0.333... (repeats). 1/7 = 0.142857142857... (repeats every 6 digits). 1/4 = 0.25 (terminates because 4 = 2²).

Use the fraction calculator to verify your mental conversions, and practice with the fraction quiz.