IP subnet calculator
Work out the network, broadcast, mask and host range for any IPv4 or IPv6 address, and split a network into smaller subnets.
How to use the IP subnet calculator
- Type an address with a prefix, such as 192.168.1.10/24 or 2001:db8::1/64.
- Read the network, range and other details. The IP version is detected automatically.
- Open Split into smaller subnets to plan a network.
Frequently asked questions
What is a CIDR prefix?
The number of leading bits that identify the network. /24 equals the mask 255.255.255.0 and gives 256 addresses.
Why are two IPv4 addresses not usable?
The first is the network address and the last is the broadcast address, except in /31 and /32 networks.
Does IPv6 have a broadcast address?
No. IPv6 uses multicast instead, so every address in the prefix can be assigned. A /64 is the standard size for one network.
Can I enter a subnet mask instead of a prefix?
Yes. Type the address, a space and the mask, for example 10.0.0.5 255.255.252.0.
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