IPv4 CIDR and Subnet Calculator
Calculate IPv4 network details, usable host ranges, binary representations, and smaller subnets from a CIDR block.
IPv4 and CIDR calculator
Enter an address such as 192.168.10.42/24.
Network input
Accepted formats
192.168.1.10
192.168.1.10/24
10.20.30.40/16
An address without a prefix is treated as a single-host /32 network.
Network calculation
Enter an IPv4 address
Network, broadcast, mask, usable range, and binary details will appear here.
Network addressing
Understand the boundaries and capacity of an IPv4 subnet
CIDR calculations help network engineers plan address ranges, configure routing, review firewall rules, and troubleshoot connectivity.
Verify network boundaries
The network and broadcast addresses define the traditional boundaries of a subnet. Devices should normally receive addresses within the usable host range.
Plan smaller subnets
Increasing the prefix length divides a network into smaller blocks. Each additional subnet bit doubles the number of subnets and halves their address capacity.
Guide
About IPv4 CIDR and Subnet Calculator
CIDR notation combines an IPv4 address with a prefix length that identifies the network portion.
This calculator derives network boundaries, masks, address counts, host ranges, and smaller subnet divisions.
Network planning should also account for routing, reserved addresses, platform conventions, and organizational policy.
Calculated network details
The tool derives common values from an IPv4 CIDR block.
- Network address
- Broadcast address
- Subnet mask
- Wildcard mask
- Total addresses
- Usable host range
Prefix length meaning
A larger prefix reserves more bits for the network and leaves fewer addresses for hosts.
Subnet splitting
Increasing the prefix length divides a network into smaller equal-sized blocks.
Special subnet cases
/31 and /32 networks have special uses and should not always be interpreted with traditional host-range assumptions.
FAQ
Frequently asked questions
What does /24 mean?
It means the first 24 bits identify the network, leaving 8 bits for addresses within the block.
What is the network address?
It is the first address in the CIDR block and identifies the subnet.
What is the broadcast address?
In traditional IPv4 subnets, it is the final address used to reach all hosts on the subnet.
How many addresses are in a /24?
A /24 contains 256 total IPv4 addresses.
Why are usable hosts often two fewer?
Traditional subnets reserve the network and broadcast addresses.
Does the calculator support IPv6?
This page is focused on IPv4 CIDR calculations.
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