# Octal to Decimal Converter

Enter an octal number below to convert it to decimal.

## Decimal Number:

### Steps to Convert to Decimal

Learn how we calculated this below

## How to Convert Octal to Decimal

The octal number system is a base 8 number system since it uses just eight digits, 0 to 7. On the other hand, decimal is a base 10 number system since it uses ten digits, 0 to 9.

When working with octal numbers, you’ll often need to convert the number to its decimal value since most people use the decimal system.

The base 8 system is often used in legacy computing applications because a single octal digit can represent three binary bits, which are cleanly divisible in 6, 12, 24, and 36-bit computer systems. Most modern computer systems, however, are 16, 32, or 64-bit systems which are cleanly divisible into base 16 numbers, so the hexadecimal system is more commonly used today.

To convert an octal number to a decimal, you can use the positional notation method. To use this method, multiply each octal digit number from the rightmost number to the left by 8 to the power of n, where n is the distance from the right.

So, reading the octal number from right to left, the furthest digit to the right is equal to the digit times 80. The digit that is one position from the right is equal to the digit times 81.

### Octal to Decimal Formula

The octal to decimal formula can be expressed as:

decimal number10 = (d0 × 80) + (d1 × 81) + … + (dn – 1 × 8n – 1)

When using the formula, d0 is the octal digit furthest to the right, d1 is the digit one position from the right, and dn – 1 is the digit furthest to the left.

For example, let’s convert the octal number 730 to decimal.

decimal number10 = (7 × 82) + (3 × 81) + (0 × 80)
decimal number10 = 448 + 24 + 0
decimal number10 = 472

## Octal to Decimal Conversion Table

The table below shows octal numbers and the equivalent decimal number values.

Octal numbers converted to the equivalent decimal values
Octal Number Decimal Number
0 0
1 1
2 2
3 3
4 4
5 5
6 6
7 7
10 8
11 9
12 10
13 11
14 12
15 13
16 14
17 15
20 16
21 17
22 18
23 19
24 20
25 21
26 22
27 23
30 24
31 25
32 26
33 27
34 28
35 29
36 30
37 31
40 32
100 64
200 128
400 256
1000 512
2000 1024
4000 2048