0.8 as a fraction is 4/5. As a percent it is 80%. The fraction is in lowest terms: the numerator and denominator share no common factor other than 1.
How to convert 0.8 to a fraction
Step 1. Write 0.8 over a power of ten. It has 1 digit after the decimal point, so the denominator is 10: 0.8 = 8/10.
Step 2. Find the greatest common divisor of 8 and 10, which is 2.
Step 3. Divide the top and bottom by 2: 8 ÷ 2 = 4 and 10 ÷ 2 = 5. The result is 4/5.
The denominator 5 factors into 5, so this decimal terminates, as every decimal that is written with a finite number of digits does.
0.8 compared with nearby decimals
These decimals have the same number of places as 0.8, so the same method gives their fractions:
| Decimal | Fraction | Percent |
|---|---|---|
| 0.6 | 3/5 | 60% |
| 0.7 | 7/10 | 70% |
| 0.9 | 9/10 | 90% |
| 1 | 1 | 100% |
Multiples of 0.8
Scaling the fraction is a quick way to check your work. Each row multiplies 0.8 (4/5) by a whole number:
| Multiple | Decimal | Fraction | Mixed number |
|---|---|---|---|
| 2 × 0.8 | 1.6 | 8/5 | 1 3/5 |
| 3 × 0.8 | 2.4 | 12/5 | 2 2/5 |
| 4 × 0.8 | 3.2 | 16/5 | 3 1/5 |
| 5 × 0.8 | 4 | 4 | 4 |
| 10 × 0.8 | 8 | 8 | 8 |
When to keep the fraction
A fraction with denominator 5 is not a standard ruler fraction, so for measuring you may need the nearest 1/16 or 1/32 instead. Use the calculator above and choose a precision to round 0.8 to the closest ruler fraction.
Change the decimal in the calculator above to convert any other number; leave the precision on Exact fraction for the precise answer.