IP Address Formats: Decimal, Binary, Hex, and How to Convert

Understand every IP address format, learn step-by-step conversions, and see why each representation matters in real networking.

When most people think of an IP address, they picture four numbers separated by dots: 192.168.1.1. That is the dotted-decimal IP address format, and it is designed to be easy for humans to read. But your computer does not think in decimal. It thinks in binary—ones and zeros.

The same address can also be written in hexadecimal, as a single large integer, or even in octal. Each IP address format exists because different contexts demand different representations. Network engineers converting IP to binary to calculate subnets. Developers storing IPs as integers for database efficiency. Security analysts reading hex in packet dumps. Same address, different lens.

This guide walks through every major IP address format. It shows you exactly how to convert between them with real math. It also explains when and why each one matters. IP addresses are just one type of network identifier. Devices also use MAC addresses at the hardware level. These identifiers work at different layers of the OSI model. Whether you are studying for a certification, writing network code, or just curious, this guide has you covered. You will leave able to read any IP address format with confidence.

The Dotted-Decimal Format

Dotted-decimal is the everyday IPv4 format, like 192.168.1.1. It splits the 32-bit address into four 8-bit octets. Each octet is written in decimal, from 0 to 255, separated by dots. It exists for one reason: people read decimal far more easily than binary.

Dotted-decimal notation is the standard IP address format for IPv4. It looks like this:

192.168.1.1

The address is made up of four groups called octets, separated by dots. Each octet represents 8 bits of the underlying 32-bit address. The term “octet” literally means a group of eight, referring to the 8 binary digits that make up each section.

Because each octet is 8 bits wide, the values run from 0 to 255. The smallest is 0, with all eight bits off. The largest is 255, with all eight bits on. If you ever see a number outside this range in an IP address, something is wrong.

  192   .   168   .    1    .    1
   |         |        |        |
 Octet 1  Octet 2  Octet 3  Octet 4

Each octet: 8 bits = values 0 through 255
Total:      4 octets x 8 bits = 32 bits

This format was chosen because humans are terrible at reading long strings of binary. Breaking the 32-bit address into four decimal numbers makes it manageable. You can quickly tell someone to ping 192.168.1.1, but try telling them to ping 11000000101010000000000100000001 over the phone.

Dotted-decimal is what you will see in router configurations, DNS records, firewall rules, and virtually every networking interface. When you check your public IP, the result comes back in this format.

Binary Format

Binary is the IP address as the computer sees it: a 32-bit string of ones and zeros. Each octet becomes 8 bits. Binary is essential for subnetting, because the subnet mask is applied with a bitwise AND. Decimal hides this layer, but the network runs on the bits.

Binary is the native IP address format as far as your computer is concerned. Every IP address is fundamentally a 32-bit binary number. The dotted-decimal notation is just a convenience layer on top of it.

To convert an IP address to binary, you convert each octet independently using positional values. Each bit position in an octet has a fixed value:

The technique is simple. Start with the leftmost place value, 128. If the octet is greater than or equal to 128, write a 1 and subtract 128. If not, write a 0. Move to the next place value, 64, and repeat. Continue until all 8 bits are filled.

Octet 1: 192
  192 ≥ 128? Yes → 1, remainder = 64
   64 ≥  64? Yes → 1, remainder = 0
    0 ≥  32? No  → 0
    0 ≥  16? No  → 0
    0 ≥   8? No  → 0
    0 ≥   4? No  → 0
    0 ≥   2? No  → 0
    0 ≥   1? No  → 0
  Result: 11000000

Octet 2: 168
  168 ≥ 128? Yes → 1, remainder = 40
   40 ≥  64? No  → 0
   40 ≥  32? Yes → 1, remainder = 8
    8 ≥  16? No  → 0
    8 ≥   8? Yes → 1, remainder = 0
    0 ≥   4? No  → 0
    0 ≥   2? No  → 0
    0 ≥   1? No  → 0
  Result: 10101000

Octet 3: 1
  Result: 00000001

Octet 4: 1
  Result: 00000001

Full IP address in binary:
11000000.10101000.00000001.00000001

Why Binary Matters for Subnetting

The real reason every networking student needs to understand IP address binary is subnetting. Your computer must decide whether a destination IP is local or needs routing. To do this, it performs a bitwise AND between the IP address and the subnet mask.

IP Address:    11000000.10101000.00000001.00000001  (192.168.1.1)
Subnet Mask:   11111111.11111111.11111111.00000000  (255.255.255.0)
               ─────────────────────────────────────
AND Result:    11000000.10101000.00000001.00000000  (192.168.1.0)

The result is the network address. Any device that produces
the same network address after the AND operation is on the
same local subnet.

This is entirely a binary operation. You cannot do it in decimal without first converting. That is why understanding IP to binary conversion is not optional—it is the foundation of every subnetting calculation. Our subnet calculator automates this. But knowing the mechanics yourself is what turns configuration into real understanding.

Hexadecimal Format

Hexadecimal is base-16, and each hex digit maps to exactly 4 bits. So one 8-bit octet becomes two hex digits. This makes hex a compact bridge between binary and decimal. You meet it in packet captures, IPv6 addresses, and low-level network code.

Hexadecimal (base-16) provides a compact way to represent binary data. Each hex digit represents exactly 4 bits, which means each 8-bit octet can be written as exactly 2 hex digits. This makes hexadecimal a natural middle ground. It is shorter than binary and closer to the bit patterns than decimal.

The hex digits are 0 through 9 and A through F. The letters map as A=10, B=11, C=12, D=13, E=14, and F=15.

Converting Decimal to Hex

To convert an octet to hex, divide by 16. The quotient is the first hex digit; the remainder is the second.

Octet 1: 192 ÷ 16 = 12 remainder 0  → C0
Octet 2: 168 ÷ 16 = 10 remainder 8  → A8
Octet 3:   1 ÷ 16 =  0 remainder 1  → 01
Octet 4:   1 ÷ 16 =  0 remainder 1  → 01

Hexadecimal IP address: C0.A8.01.01
With 0x prefix:         0xC0A80101

The 0x prefix comes from languages like C and Python. It signals that the number is in hexadecimal. You will see both dotted hex (C0.A8.01.01) and the flat form (0xC0A80101), depending on context.

Where Hex Shows Up

• Packet captures: Tools like Wireshark display raw packet data in hexadecimal. If you are analyzing network traffic, you are reading hex.
• IPv6 addresses: The entire IPv6 address format is hexadecimal (e.g., 2001:0db8:85a3::8a2e:0370:7334). Understanding hex in IPv4 gives you a head start. Our IPv4 vs. IPv6 comparison covers the differences between both protocols.
• MAC addresses: Written in hex, like 00:1A:2B:3C:4D:5E. If you work with both MAC and IP data, hex is the common language.
• Low-level programming: Embedded systems, firmware, and network stack code frequently represent IP addresses in hexadecimal format.

Integer (32-bit) Format

The integer format treats the whole address as one unsigned 32-bit number. So 192.168.1.1 becomes 3232235777. Databases and logs use it for two reasons: it takes only 4 bytes, and range queries become simple integer comparisons.

Every IPv4 address can be expressed as a single unsigned 32-bit integer. This format treats the entire 32-bit number as one value. It does not split the address into four octets.

The formula is:

Integer = (Octet1 × 2^24) + (Octet2 × 2^16) + (Octet3 × 2^8) + Octet4

Which equals:
Integer = (Octet1 × 16,777,216) + (Octet2 × 65,536) + (Octet3 × 256) + Octet4

192 × 16,777,216 = 3,221,225,472
168 ×     65,536 =    11,010,048
  1 ×        256 =           256
  1 ×          1 =             1
                    ─────────────
Total:              3,232,235,777

So 192.168.1.1 = 3232235777 as a 32-bit integer.

Why Store IPs as Integers?

Databases and software often store IP addresses in integer format for two practical reasons:

• Storage efficiency: A 32-bit integer takes exactly 4 bytes. Storing the dotted-decimal string "192.168.1.1" takes 11 to 15 bytes depending on the address. When you have millions of log entries, that difference adds up.
• Range queries: Finding all IPs in a block becomes one integer comparison, like WHERE ip_int BETWEEN 3232235776 AND 3232236031. String storage needs complex parsing or padding for the same result.

To convert an integer back to dotted-decimal, you reverse the process: divide repeatedly by 256 and take the remainders.

3232235777 ÷ 256 = 12625921 remainder 1   → Octet 4 = 1
  12625921 ÷ 256 =    49319 remainder 1   → Octet 3 = 1
     49319 ÷ 256 =      192 remainder 168 → Octet 2 = 168
                                                Octet 1 = 192

Result: 192.168.1.1  (reading octets 1 through 4)

IP Address Classes

Classful addressing split IPv4 into classes A through E by the leading bits of the first octet. Classes A, B, and C were for unicast, D for multicast, and E reserved. CIDR replaced this system in 1993. The class labels survive as shorthand and on certification exams.

In the early internet, IPv4 addresses were divided into five classes. The split was based on the leading bits of the first octet. This system, called classful networking, set how many bits were network and how many were host.

Classful networking was replaced by CIDR (Classless Inter-Domain Routing) in 1993 because the fixed class sizes were wildly inefficient. A company needing 300 addresses would get an entire Class B with 65,534 host slots—wasting tens of thousands of addresses. CIDR allows subnet masks of any length, so you can allocate exactly what you need. Our subnetting guide walks through CIDR notation and subnet calculations step by step. For a focused breakdown of the slash number itself, see CIDR Notation Explained.

Despite being technically obsolete, IP address classes still matter. Certification exams test them, and the private ranges are defined by class. Networking professionals also use the class labels as everyday shorthand.

What about Class E? The 240.0.0.0/4 block stays reserved today. A long-running IETF proposal to open it for normal unicast use (draft-schoen-intarea-unicast-240) expired in 2025 with no adoption. Many operating systems already accept 240/4 on private networks, and large clouds use it internally. But it is still not routable on the public internet.

Private Address Ranges

RFC 1918 reserved specific blocks within Classes A, B, and C for private (non-routable) use. These are the addresses used on internal networks behind routers and firewalls:

Have you connected to home Wi-Fi and seen an IP starting with 192.168? That is a Class C private address. Enterprise networks tend to use the 10.x.x.x range because it offers far more addresses for large-scale internal use. For more on how private and public addresses interact, see our guide on public vs. private IP addresses.

Special and Reserved Addresses

Several IPv4 blocks are reserved for specific jobs, not normal hosts. Examples include 127.0.0.0/8 for loopback and 169.254.0.0/16 for link-local APIPA. Others cover multicast, broadcast, documentation, and carrier-grade NAT. Knowing them speeds up troubleshooting and shows up on certification exams.

Not every IP address format value is available for regular use. Several blocks are reserved for specific functions defined by various RFCs. Knowing these is essential for troubleshooting and certification exams alike.

Understanding these reserved addresses prevents common mistakes. For example, a server set to listen on 0.0.0.0 does not lack an IP. It is listening on every available interface. And a user whose IP is 169.254.x.x has a DHCP problem, not DNS or routing. You can check any address with a reverse DNS lookup to see what it resolves to.

Converting Between Formats

Converting between formats follows fixed rules you can do by hand. Use place values to move between decimal and binary. Divide by 16 for hexadecimal. Use powers of 256 for the integer form. The table below shows two addresses in all four formats at once.

Here is a quick-reference walkthrough for converting the IP address format in each direction. We will use 10.0.75.200 as our example throughout.

Decimal to Binary

For each octet, use the subtraction method with place values 128, 64, 32, 16, 8, 4, 2, 1:

10  = 0 + 0 + 0 + 0 + 8 + 0 + 2 + 0  = 00001010
0   = 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0  = 00000000
75  = 0 + 64 + 0 + 0 + 8 + 0 + 2 + 1 = 01001011
200 = 128 + 64 + 0 + 0 + 8 + 0 + 0 + 0 = 11001000

Binary: 00001010.00000000.01001011.11001000

Binary to Decimal

For each 8-bit group, add up the place values where the bit is 1:

00001010 = 8 + 2                   = 10
00000000 = 0                       = 0
01001011 = 64 + 8 + 2 + 1         = 75
11001000 = 128 + 64 + 8           = 200

Decimal: 10.0.75.200

Decimal to Hexadecimal

Divide each octet by 16. The quotient is the first hex digit, the remainder is the second:

10  ÷ 16 = 0 remainder 10  → 0A
0   ÷ 16 = 0 remainder 0   → 00
75  ÷ 16 = 4 remainder 11  → 4B
200 ÷ 16 = 12 remainder 8  → C8

Hex: 0A.00.4B.C8  (or 0x0A004BC8)

Decimal to Integer

10  × 16,777,216 =   167,772,160
0   ×     65,536 =             0
75  ×        256 =        19,200
200 ×          1 =           200
                    ─────────────
Total:              167,791,560

So 10.0.75.200 = 167791560 as a 32-bit integer.

All Formats at a Glance

To verify your work or convert a batch quickly, use our IP address converter. It shows results in all formats at once.

Related Tools & Resources

Put these formats into practice with our free networking tools. Convert any address across binary, hex, and integer, or check your public IP in seconds. Each tool runs in your browser, with nothing to install. The guides below go deeper on subnetting and addressing.

• IP Address Converter — convert any address across binary, hexadecimal, and integer formats.
• Subnet Calculator — work out network and host ranges from any CIDR block.
• CIDR Notation Explained — how to read any /8 through /32 prefix.
• What Is My IP Address — see your own public IP in dotted-decimal.
• IPv4 vs IPv6 — how the two address formats differ.
• Public vs Private IP Addresses — where the RFC 1918 ranges fit.

Frequently Asked Questions

Short answers to the questions people ask most about IP address formats. These cover why dotted-decimal exists, how to convert to binary by hand, and when each format is used.