Convert Decimal to Octal
1 Decimal (dec) = 1 Octal (oct). Use the free converter below to instantly convert any decimal value to octal, or view the full conversion table and formula.
1 dec = 1 oct
Decimal to Octal Conversion Table
How to Convert Decimal to Octal
To convert decimal to octal, repeatedly divide the number by 8 and note the remainders. Read the remainders from bottom to top. For example, 100 in decimal: 100÷8=12 R4, 12÷8=1 R4, 1÷8=0 R1 → 144 in octal.
Worked Example: Convert 7 dec to oct
Start with the value in decimal
7 dec
Apply the formula
Repeatedly divide by 8, read remainders bottom-to-top
Calculate the result
7 dec = 7 oct
Decimal to Octal Examples
0 dec is equal to 0 oct. Using the formula Repeatedly divide by 8, read remainders bottom-to-top, 0 dec converts to 0 oct.
1 dec is equal to 1 oct. Using the formula Repeatedly divide by 8, read remainders bottom-to-top, 1 dec converts to 1 oct.
2 dec is equal to 2 oct. Using the formula Repeatedly divide by 8, read remainders bottom-to-top, 2 dec converts to 2 oct.
7 dec is equal to 7 oct. Using the formula Repeatedly divide by 8, read remainders bottom-to-top, 7 dec converts to 7 oct.
8 dec is equal to 10 oct. Using the formula Repeatedly divide by 8, read remainders bottom-to-top, 8 dec converts to 10 oct.
10 dec is equal to 12 oct. Using the formula Repeatedly divide by 8, read remainders bottom-to-top, 10 dec converts to 12 oct.
15 dec is equal to 17 oct. Using the formula Repeatedly divide by 8, read remainders bottom-to-top, 15 dec converts to 17 oct.
16 dec is equal to 20 oct. Using the formula Repeatedly divide by 8, read remainders bottom-to-top, 16 dec converts to 20 oct.
Converting Octal to Decimal
Need the reverse conversion? Use the table below for a quick reference converting octal back to decimal.
| Octal (oct) | Decimal (dec) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 7 | 7 |
| 10 | 8 |
| 17 | 15 |
| 20 | 16 |
Decimal to Octal FAQ
How do I convert decimal to octal?
Repeatedly divide the decimal number by 8 and record the remainders. Read the remainders from bottom to top. For example, 493 ÷ 8 = 61 R5, 61 ÷ 8 = 7 R5, 7 ÷ 8 = 0 R7 → 755 in octal.
What is 255 in octal?
255 in decimal equals 377 in octal. This represents the maximum value of a single byte.
What are octal numbers used for?
Octal is primarily used in Unix/Linux file permissions (e.g., chmod 644 sets read/write for owner, read-only for group and others). Each octal digit maps to 3 binary bits.
Understanding Decimal and Octal
What is a Decimal (dec)?
The decimal (dec) is a specialized unit of number systems. It is commonly abbreviated as dec and relates to octal by a factor of 1.
What is an Octal (oct)?
The octal (oct) is a specialized unit of number systems. It is commonly abbreviated as oct and relates to decimal by a factor of 1.