Decimal to Octal Converter
Use this converter to quickly transform decimal numbers into octal. Useful tool for students, programmers, and technology professionals.
Updated at: 05/10/2025Enter a decimal number to see the octal conversion.
Enter a decimal number to see the result.
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How to Convert Decimal to Octal
Decimal to octal conversion is a useful process in computer science and digital systems. It involves changing numbers from base-10, the standard numerical system, to base-8, which uses only digits from 0 to 7.
A Decimal to Octal Converter simplifies this task by instantly converting any decimal value into its octal equivalent. This saves time, prevents errors, and helps students and professionals visualize numerical data in octal format.
What Is Decimal to Octal Conversion?
Decimal to octal conversion means translating a number from base-10 (using digits 0–9) into base-8 (using digits 0–7). Octal is particularly useful in computing because it's a more compact representation of binary numbers, with each octal digit corresponding to three binary digits.
This type of conversion is common in systems where memory addresses and data permissions are often represented in octal, such as in Unix file permissions.
How Does a Decimal to Octal Converter Work?
The converter divides the decimal number repeatedly by 8. At each step, the remainder is recorded. These remainders, read from bottom to top (last to first), form the octal number. The tool automates this division process to provide quick and accurate results.
For example:
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Decimal: 100
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Steps:
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100 ÷ 8 = 12 remainder 4
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12 ÷ 8 = 1 remainder 4
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1 ÷ 8 = 0 remainder 1
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Octal: 144
Decimal to Octal Conversion Formula
The conversion process follows these steps:
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Divide the decimal number by 8.
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Record the remainder.
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Continue dividing the quotient by 8 until the result is 0.
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Read the remainders in reverse order.
Example:
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Decimal: 45
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45 ÷ 8 = 5 remainder 5
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5 ÷ 8 = 0 remainder 5
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Octal: 55
Conversion Examples
Here are some examples showing decimal to octal conversions:
Decimal | Division Steps | Octal |
---|---|---|
10 | 10 ÷ 8 = 1 R2, 1 ÷ 8 = 0 R1 | 12 |
64 | 64 ÷ 8 = 8 R0, 8 ÷ 8 = 1 R0, 1 ÷ 8 = 0 R1 | 100 |
255 | 255 ÷ 8 = 31 R7, 31 ÷ 8 = 3 R7, 3 ÷ 8 = 0 R3 | 377 |
512 | 512 ÷ 8 = 64 R0, 64 ÷ 8 = 8 R0, 8 ÷ 8 = 1 R0, 1 ÷ 8 = 0 R1 | 1000 |
This table shows how decimal numbers break down into their base-8 equivalents through division.
Why Use Octal Numbers?
Octal numbers are used in:
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Operating Systems: Unix and Linux file permissions (e.g., chmod 755).
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Digital Electronics: Compact representation of binary.
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Memory Addressing: Easier interpretation of byte groups.
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Embedded Systems: Simpler representation of control codes and register values.
Octal offers a balance between compactness and readability in systems that work closely with binary data.
Advantages of a Decimal to Octal Converter
Using a digital tool to convert decimal to octal has several benefits:
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Speed: Instant results, no calculations needed.
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Precision: No human error in the division process.
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Learning Aid: Visual breakdown of the conversion steps.
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Accessibility: Useful for students, educators, and developers.
These tools streamline tasks that involve octal number systems, especially when dealing with large or complex values.
Frequently Asked Questions
How do you manually convert decimal to octal?
To convert manually, divide the decimal number by 8 repeatedly. Record the remainders at each step. Once the quotient reaches zero, reverse the order of the remainders to get the octal number.
Example:
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83 ÷ 8 = 10 R3
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10 ÷ 8 = 1 R2
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1 ÷ 8 = 0 R1
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Octal: 123
What are octal numbers used for?
Octal numbers are used in computing to represent binary data in a condensed form. Common uses include:
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File permissions (e.g., 777 in Unix)
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Memory locations
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Machine-level programming
What digits are used in octal?
Octal uses only digits from 0 to 7. Each digit represents exactly three binary digits (bits). For example:
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7 = 111
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5 = 101
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0 = 000
Can decimals with fractions be converted to octal?
Yes, fractional decimal numbers can be converted. The integer part is converted using division. The fractional part is multiplied by 8 repeatedly, taking the integer part of each result.
Example:
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Decimal: 12.375
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Integer: 12 → 14 (octal)
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Fraction: 0.375 × 8 = 3.0 → .3
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Octal: 14.3
Is octal still used today?
Yes, although less common than hexadecimal, octal is still used in specific systems like Unix permissions and some legacy software. It remains a valuable part of computing history and education.
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