IPv4 Subnet Calculator

Enter an IPv4 network block in CIDR notation, then choose a prefix, address capacity, or subnet count. The calculator shows network, broadcast, usable hosts, wildcard mask, and generated subnet ranges.

Network block and subnet size

Enter an IPv4 network block in CIDR notation, then choose a prefix, address capacity, or subnet count. The calculator shows network, broadcast, usable hosts, wildcard mask, and generated subnet ranges.

Enter an IPv4 address with a CIDR prefix, for example 192.168.1.0/24. Host bits are normalized to the network boundary.

Subnet details

Network address

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Usable-host range

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Broadcast address

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Wildcard mask

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CIDR prefix

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Subnet mask
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First usable host
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Last usable host
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Total IP addresses
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Usable hosts
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Block size / increment
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Address class
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Generated subnets

# CIDR Network Usable-host range Broadcast

No subnets to display yet.

What this tool does

The IPv4 subnet calculator derives the network address, broadcast address, usable-host range, subnet mask, wildcard mask, and address counts for an IPv4 CIDR block.

How to use the tool

  1. Enter an IPv4 address with a CIDR prefix, such as 192.168.1.10/24.
  2. Choose a subnet prefix, required address capacity, or number of equal subnets.
  3. Review the calculated values and generated subnet table; click or tap a result to copy it.

Useful applications

  • Validate network and broadcast addresses while configuring routers, firewalls, or servers.
  • Plan equal-size subnet splits within an existing IPv4 network.
  • Compare CIDR prefixes, subnet masks, total addresses, and usable-host capacity.

Notes and limitations

  • If host bits are present in the input, the address is normalized to the corresponding network boundary.
  • Usable-host counts follow conventional IPv4 subnet rules; /31 point-to-point links and /32 host routes are handled separately.
  • Class A–E information is historical context. Modern routing and allocation use CIDR prefixes.

Frequently asked questions

Why does the address sometimes change after I enter it?

The calculator clears host bits so the displayed address is the actual network boundary for the selected CIDR prefix.

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