IP Subnet Calculator
What is an IPv4 subnet calculator?
The IPv4 Subnet Calculator on UnwanIP helps analyze an IPv4 address and determine network information from a CIDR prefix or subnet mask. It can calculate the network address, broadcast address, usable host range, number of addresses and subnet mask.
These calculations are commonly used for local network administration, router configuration, subnet design and IP address planning.
How is an IPv4 address structured?
An IPv4 address contains 32 bits and is normally written as four decimal numbers separated by dots, for example 192.168.1.10.
Each section can range from 0 to 255 because each octet represents 8 bits.
What does CIDR mean in IPv4?
CIDR notation defines the number of bits used for the network portion of an IPv4 address. For example, in 192.168.1.10/24, the /24 means that the first 24 bits identify the network.
A larger CIDR prefix generally creates a smaller subnet with fewer addresses.
Common IPv4 CIDR sizes
/24= 256 total addresses./25= 128 addresses./26= 64 addresses./27= 32 addresses./28= 16 addresses./29= 8 addresses./30= 4 addresses./31= 2 addresses./32= 1 address.
What is an IPv4 subnet mask?
A subnet mask determines which part of an IPv4 address represents the network and which part identifies a host within that network.
For example, 255.255.255.0 corresponds to /24, while 255.255.255.128 corresponds to /25.
What is an IPv4 network address?
The network address is the first address in a subnet and represents the network itself.
For the subnet 192.168.1.0/24, the network address is 192.168.1.0.
What is a broadcast address?
The broadcast address is the last address in a traditional IPv4 subnet and can be used to send traffic to all devices in the broadcast domain.
For 192.168.1.0/24, the broadcast address is 192.168.1.255.
How is the usable host range calculated?
In most traditional IPv4 subnets, usable host addresses begin immediately after the network address and end immediately before the broadcast address.
For 192.168.1.0/24, the traditional usable host range is 192.168.1.1 through 192.168.1.254.
What are private IPv4 addresses?
Some IPv4 address ranges are reserved for private networks and are not directly routed across the public Internet.
10.0.0.0/8172.16.0.0/12192.168.0.0/16
These ranges are widely used in homes, offices, data centers and other internal networks.
Public vs private IPv4 addresses
A public IPv4 address can be used for communication across the Internet and is visible to external Internet services. A private IPv4 address normally operates only inside a local network.
Multiple devices can share a single public IPv4 address through technologies such as Network Address Translation (NAT).
What are /31 and /32 networks?
A /31 subnet can be used for certain point-to-point network links, while a /32 represents one IPv4 address.
These prefixes have different use cases from traditional subnets that reserve separate network and broadcast addresses.
When should you use an IPv4 subnet calculator?
- When dividing a network into smaller subnets.
- When assigning static IP addresses.
- When configuring routers or firewalls.
- When checking CIDR prefixes and subnet masks.
- When calculating available address capacity.
- When identifying network and broadcast addresses.
- When planning business network addressing.
Frequently asked questions about IPv4 subnetting
How many bits are in an IPv4 address?
An IPv4 address contains 32 bits, normally divided into four 8-bit octets.
How many addresses are in a /24 subnet?
A /24 subnet contains 256 total IPv4 addresses. In traditional subnetting, 254 are normally usable by hosts after excluding the network and broadcast addresses.
Which subnet mask is equivalent to /24?
The subnet mask equivalent to /24 is 255.255.255.0.
Are all IPv4 addresses usable on the Internet?
No. Some ranges are private or reserved for specific technical purposes and are not routed on the public Internet.
What is the difference between a network address and a broadcast address?
The network address identifies the subnet itself, while the broadcast address is traditionally used to communicate with all hosts within the same IPv4 broadcast domain.
Can IPv4 and IPv6 be used on the same network?
Yes. Many modern networks use dual-stack configurations that support IPv4 and IPv6 at the same time.