Octal to Decimal Converter - Convert Base 8 to Base 10 Numbers

Octal Number (Base 8)

Decimal Number (Base 10)

Result:

12₈ = 10₁₀

🔥 Popular Converters

Quick access to most used tools

📏Length ⚖️Weight 🌡️Temperature 📐Area 🥤Volume 🚀Speed

How Octal to Decimal Conversion Works

Input Octal

Enter base 8 number

Multiply by Powers

Each digit × 8^position

Sum Results

Add all products

Σ(d × 8ⁿ)

Conversion formula

Step-by-Step Calculation

Converting 12₈ to Decimal:

Position 1: 1 × 8^1 = 1 × 8 = 88

Position 0: 2 × 8^0 = 2 × 1 = 22

Sum: 8 + 2 = 10₁₀

Octal to Decimal Conversion Table

Octal	Decimal	Octal	Decimal	Octal	Decimal
0	0	17	15	36	30
1	1	20	16	37	31
2	2	21	17	40	32
3	3	22	18	41	33
4	4	23	19	42	34
5	5	24	20	43	35
6	6	25	21	44	36
7	7	26	22	45	37
10	8	27	23	46	38
11	9	30	24	47	39
12	10	31	25	50	40
13	11	32	26	51	41
14	12	33	27	52	42
15	13	34	28	53	43
16	14	35	29	54	44

Number System Progression Chart

Octal: 10

Decimal:8

Binary:1000

Hex:8

Octal: 20

Decimal:16

Binary:10000

Hex:10

Octal: 40

Decimal:32

Binary:100000

Hex:20

Octal: 100

Decimal:64

Binary:1000000

Hex:40

Octal: 200

Decimal:128

Binary:10000000

Hex:80

Octal: 377

Decimal:255

Binary:11111111

Hex:FF

Practice Problems

Problem 1:

Convert 25₈ to decimal

Solution: 2×8¹ + 5×8⁰ = 16 + 5 = 21₁₀

Problem 2:

Convert 100₈ to decimal

Solution: 1×8² + 0×8¹ + 0×8⁰ = 64 + 0 + 0 = 64₁₀

Problem 3:

Convert 144₈ to decimal

Solution: 1×8² + 4×8¹ + 4×8⁰ = 64 + 32 + 4 = 100₁₀

Problem 4:

Convert 377₈ to decimal

Solution: 3×8² + 7×8¹ + 7×8⁰ = 192 + 56 + 7 = 255₁₀

Problem 5:

Convert 1000₈ to decimal

Solution: 1×8³ + 0×8² + 0×8¹ + 0×8⁰ = 512₁₀

Daily Uses of Octal to Decimal Conversion

Converting Unix file permissions from octal to understand access levels

Programming tasks requiring conversion between number systems

Digital electronics work involving octal representation of binary data

Computer science education and learning number system concepts

Assembly language programming where octal addresses need decimal equivalents

Export Options

Quick Reference

📏1 meter

3.28 feet

⚖️1 kilogram

2.2 pounds

🌡️0°C

32°F

🥤1 liter

0.26 gallon

Octal	Decimal	Octal	Decimal	Octal	Decimal
0	0	17	15	36	30
1	1	20	16	37	31
2	2	21	17	40	32
3	3	22	18	41	33
4	4	23	19	42	34
5	5	24	20	43	35
6	6	25	21	44	36
7	7	26	22	45	37
10	8	27	23	46	38
11	9	30	24	47	39
12	10	31	25	50	40
13	11	32	26	51	41
14	12	33	27	52	42
15	13	34	28	53	43
16	14	35	29	54	44

Octal	Decimal	Octal	Decimal	Octal	Decimal
0	0	17	15	36	30
1	1	20	16	37	31
2	2	21	17	40	32
3	3	22	18	41	33
4	4	23	19	42	34
5	5	24	20	43	35
6	6	25	21	44	36
7	7	26	22	45	37
10	8	27	23	46	38
11	9	30	24	47	39
12	10	31	25	50	40
13	11	32	26	51	41
14	12	33	27	52	42
15	13	34	28	53	43
16	14	35	29	54	44