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IP Address Tools

IP converter, subnet calculator, CIDR, binary/hex conversion, IPv4/IPv6 tools

IP Address Converter

Or enter by octets:

Subnet Calculator

CIDR Reference Table

CIDRSubnet MaskHostsNetworks in /8

IP Range Calculator

Private IP Ranges

  • 10.0.0.0/8
  • 172.16.0.0/12
  • 192.168.0.0/16
  • 127.0.0.0/8 (loopback)
  • 169.254.0.0/16 (link-local)

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Free IP Address Tools & Subnet Calculator

A complete network engineer's toolkit — convert IP addresses between decimal, binary, hexadecimal and octal representations, calculate subnet information from CIDR notation or subnet masks, and instantly identify IP classes, private ranges and broadcast addresses.

Features

IP Converter

Convert any IPv4 address between decimal, binary, hex, octal and IPv6-mapped format.

Subnet Calculator

Input any IP with CIDR prefix or subnet mask to get network address, broadcast, host range and usable host count.

CIDR Reference Table

Complete /1 to /32 reference showing subnet mask, usable hosts and network count.

Range Calculator

Calculate the total number of IPs between any two addresses.

Private IP Detection

Automatically identifies private (RFC 1918), loopback, link-local and public IP ranges.

IPv6 Mapping

Shows the IPv4-mapped IPv6 representation (::ffff:x.x.x.x) for any IPv4 address.

Who Uses This Tool?

Network EngineersDesign subnets, verify CIDR notation and plan IP address allocation.
Security AnalystsClassify IP addresses and verify whether addresses are private or public.
Networking StudentsLearn subnetting and binary IP representation with real-time conversion.
DevelopersConvert IP addresses to long integer format for storage and comparison in databases.

Frequently Asked Questions

What is a subnet mask?
A subnet mask divides an IP address into a network portion and a host portion. 255.255.255.0 (/24) means the first 24 bits identify the network and the remaining 8 bits identify individual hosts (256 addresses, 254 usable).
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation expresses a network as an IP address followed by a slash and prefix length (e.g., 192.168.1.0/24). The prefix length indicates how many bits are fixed for the network portion.
What is a private IP address?
Private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) are reserved for internal networks and are not routable on the public internet. Your home router uses these to assign addresses to your devices via DHCP.
What is a broadcast address?
The broadcast address is the last address in a subnet (e.g., 192.168.1.255 in a /24 network). Packets sent to this address are delivered to all hosts in the subnet. It cannot be assigned to an individual host.

Pro Tip

When subnetting, use the "power of 2" rule: each time you increase the prefix length by 1, you halve the subnet size. A /24 has 256 addresses, /25 has 128, /26 has 64, /27 has 32, /28 has 16. The first and last address in each subnet are reserved for network ID and broadcast.

Did You Know?

4.3 billion
IPv4 Addresses Available
IPv4 supports only 4,294,967,296 addresses — far fewer than the 8+ billion humans and tens of billions of connected devices. The last IPv4 address blocks were allocated in 2011. We are kept going by NAT (Network Address Translation), which lets thousands of devices share one public IP.
340 undecillion
IPv6 Addresses Available
IPv6 supports 2^128 addresses — approximately 340 undecillion (340 followed by 36 zeros). This is enough to assign billions of IPs to every atom on Earth's surface. IPv6 was standardised in 1998; global adoption in 2024 is around 45%.
1969
First ARPANET Message Crashed
The first message sent over ARPANET (the internet's predecessor) on October 29, 1969 was "LOGIN" — it crashed the receiving computer after just two letters ("LO"). The internet's first transmission was an accidental "Lo."

Reserved IP Address Ranges

RangeCIDRPurposeRFC
10.0.0.0 – 10.255.255.255/8Private (Class A)RFC 1918
127.0.0.0 – 127.255.255.255/8Loopback (localhost)RFC 5735
169.254.0.0 – 169.254.255.255/16Link-local (APIPA)RFC 3927
172.16.0.0 – 172.31.255.255/12Private (Class B)RFC 1918
192.168.0.0 – 192.168.255.255/16Private (Class C, home)RFC 1918
224.0.0.0 – 239.255.255.255/4MulticastRFC 5771
255.255.255.255/32BroadcastRFC 919

More Questions

What is NAT and why is my local IP different from my public IP?
NAT (Network Address Translation) allows multiple devices on a local network to share one public IP address. Your router has one public IP (assigned by your ISP) and assigns private IPs (192.168.x.x, 10.x.x.x) to all devices at home. When your device communicates with the internet, the router replaces the private IP with the public one — hiding your device's direct address.
What is a subnet mask and why does it matter?
A subnet mask divides an IP address into network and host portions. 255.255.255.0 (/24) means the first 24 bits identify the network — all devices sharing those 24 bits are on the same subnet. Routers use subnet masks to decide whether traffic goes to a local device or must be sent to the internet gateway. Incorrect subnet configuration is a common networking error.
What is the difference between a static and dynamic IP?
Dynamic IPs are assigned by DHCP each time a device connects — they can change. Static IPs are permanently assigned and never change. Home users typically have dynamic IPs (cheaper, simpler). Servers, printers and cameras need static IPs so they can be reliably reached. ISPs charge extra for static public IPs.

Common Mistakes

Exposing internal IP addresses in public APIs
Returning internal IPs (192.168.x.x, 10.x.x.x) in API responses reveals your network topology to potential attackers.
Strip or replace internal IPs in all external-facing API responses and logs.
Confusing /24 with 24 hosts
/24 means 24 bits for the network, leaving 8 bits for hosts = 256 addresses (254 usable). People often confuse the CIDR prefix number with the host count.
Usable hosts = 2^(32-prefix) - 2. A /24 network has 254 usable hosts, not 24.
Not planning subnets before deployment
Changing IP addressing after deployment requires reconfiguring every device — an expensive, error-prone process.
Plan your subnet structure before deploying infrastructure. Document every IP allocation.