Decimal to Fraction Calculator

The three-step method

Every terminating decimal becomes a fraction the same way. First, count how many digits sit after the decimal point. Second, write all the digits as the numerator over a 1 followed by that many zeros. Third, simplify by dividing both numbers by their greatest common divisor.

That is the whole procedure. The number of zeros in the denominator always matches the number of decimal places: tenths over 10, hundredths over 100, thousandths over 1000, and so on. The only real work is the final simplification, which is where a calculator saves you time on awkward greatest common divisors.

Common conversions worth memorising

A handful of decimals appear so often — in money, measurements and test questions — that it pays to know them on sight:

Notice that eighths produce three decimal places (0.125, 0.375, 0.625, 0.875), while quarters produce two. That regularity is a quick way to guess which fraction you are looking at before you even simplify.

Decimals greater than one

When the number has a whole part, such as 2.5 or 3.75, you have two equally valid routes. You can keep the whole number aside and convert only the decimal part — 2.5 becomes 2½ — or you can place the entire string over the power of ten and simplify into an improper fraction: 2.5 = 25/10 = 5/2. A mixed number reads more naturally in a recipe; an improper fraction is easier to feed into further arithmetic. The converter shows both so you can pick whichever the next step needs.

Repeating decimals are different

The power-of-ten trick only works for decimals that stop. A repeating decimal like 0.3333… never terminates, so 3/10, 33/100 and 333/1000 are all merely approximations. The exact answer comes from the recurring-decimal formula, which puts the repeating block over a string of nines:

If you paste a long rounded value such as 0.3333333 without marking the repeat, an honest calculator returns 3333333/10000000 — technically correct for what you typed. Switching to the “closest fraction” mode tells the tool to find the simplest fraction near that value instead, which recovers the intended 1/3.

When there is no exact fraction

Not every decimal is a fraction in disguise. Numbers whose digits never repeat and never stop — pi, the square root of two, the golden ratio — are irrational and cannot be written as a ratio of whole numbers. For those, the best any calculator can offer is a close rational approximation, like 22/7 or 355/113 for pi. The converter is upfront about this: with a bounded denominator it returns the nearest simple fraction rather than pretending an exact one exists.