0.5 as a fraction is 1/2. As a percent it is 50%. The fraction is in lowest terms: the numerator and denominator share no common factor other than 1.
How to convert 0.5 to a fraction
Step 1. Write 0.5 over a power of ten. It has 1 digit after the decimal point, so the denominator is 10: 0.5 = 5/10.
Step 2. Find the greatest common divisor of 5 and 10, which is 5.
Step 3. Divide the top and bottom by 5: 5 ÷ 5 = 1 and 10 ÷ 5 = 2. The result is 1/2.
The denominator 2 factors into 2, so this decimal terminates, as every decimal that is written with a finite number of digits does.
0.5 compared with nearby decimals
These decimals have the same number of places as 0.5, so the same method gives their fractions:
| Decimal | Fraction | Percent |
|---|---|---|
| 0.3 | 3/10 | 30% |
| 0.4 | 2/5 | 40% |
| 0.6 | 3/5 | 60% |
| 0.7 | 7/10 | 70% |
Multiples of 0.5
Scaling the fraction is a quick way to check your work. Each row multiplies 0.5 (1/2) by a whole number:
| Multiple | Decimal | Fraction | Mixed number |
|---|---|---|---|
| 2 × 0.5 | 1 | 1 | 1 |
| 3 × 0.5 | 1.5 | 3/2 | 1 1/2 |
| 4 × 0.5 | 2 | 2 | 2 |
| 5 × 0.5 | 2.5 | 5/2 | 2 1/2 |
| 10 × 0.5 | 5 | 5 | 5 |
1/2 of an inch
Tape measures and drill bits use binary fractions of an inch. Since one inch is defined as exactly 25.4 millimetres, 1/2 inch equals 1 × 25.4 ÷ 2 = 12.7000 mm.
Change the decimal in the calculator above to convert any other number; leave the precision on Exact fraction for the precise answer.