Fraction to Decimal & Percent

What the fraction to decimal calculator does

Enter a numerator and a denominator and the calculator returns the decimal value, the percentage, and the fraction reduced to lowest terms. It is the everyday conversion behind test scores (17/20 = 85%), recipe scaling, tape-measure fractions to millimetres, betting odds, and reading any ratio as a percentage. Runs in your browser.

The conversions

Decimal    = numerator ÷ denominator          3/8  = 0.375
Percentage = decimal × 100                     3/8  = 37.5%
Simplified = divide both by their GCD          18/24 → GCD 6 → 3/4

Mixed number:  2 3/8 = (2 × 8 + 3) / 8 = 19/8 = 2.375

Fractions worth memorising

Fraction	Decimal	Percent	Fraction	Decimal	Percent
1/2	0.5	50%	1/8	0.125	12.5%
1/3	0.333…	33.3%	3/8	0.375	37.5%
2/3	0.667…	66.7%	5/8	0.625	62.5%
1/4	0.25	25%	7/8	0.875	87.5%
3/4	0.75	75%	1/16	0.0625	6.25%
1/5	0.2	20%	1/6	0.1667	16.7%
1/10	0.1	10%	1/12	0.0833	8.3%

Terminating vs repeating decimals

A fraction in lowest terms gives a terminating decimal only if its denominator has no prime factors other than 2 and 5. So 3/8 (8 = 2³) terminates at 0.375, but 1/3, 1/6, 1/7 and 1/9 repeat forever: 1/7 = 0.142857 142857… The calculator shows enough digits to see the pattern; when you need exactness, keep the fraction and convert only at the final step — which is the whole argument for the Fraction Calculator over a decimal one.

Common uses

Scores and grades — 43/50 on a test is 86%.
Imperial measurements — 5/16 in = 0.3125 in = 7.94 mm; a drill chart in fractions to a decimal caliper.
Cooking — ⅔ cup is 0.667 cup ≈ 158 mL.
Finance — a share priced in eighths (old US convention) or a ratio like debt/equity read as a percentage.
Odds and probability — 3/20 odds is a 15% chance; a 1-in-8 risk is 12.5%.
Data — 214 of 1,400 responses = 15.3%.

Going the other way

Decimal to fraction: write over a power of ten, then reduce
  0.375 = 375/1000 = 3/8
  0.6   = 6/10 = 3/5
Repeating: 0.333… = 1/3, 0.1666… = 1/6, 0.142857… = 1/7   (needs algebra or a lookup)
Percent to fraction: divide by 100 and reduce   45% = 45/100 = 9/20

Frequently asked questions

Why does the decimal show 0.33333333?

1/3 has no finite decimal. The display is cut off at the calculator's precision; the true value repeats 3 forever.

How do I convert a mixed number?

Multiply the whole part by the denominator, add the numerator, and enter that over the same denominator: 1 3/4 → 7/4.

What if the numerator is bigger than the denominator?

The fraction is improper and the decimal is greater than 1 — 9/4 = 2.25 = 225%. That is fine.

How do I round a percentage properly?

Decide the precision your context needs — whole percent for a headline, one decimal for a report — and round only the final figure, not intermediate values.

Can the denominator be zero?

No. Division by zero is undefined and the calculator reports an error.

Are my values stored?

No. The calculation runs in your browser.