IPv4 Subnet Calculator

Find the network address, broadcast address and usable host range for an IP address and subnet mask.

Inputs

IP Address

CIDR Prefix (/N)

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Saved Scenarios

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Network Address

192.168.1.0

Broadcast Address

192.168.1.255

Subnet Mask

255.255.255.0

First Usable Host

192.168.1.1

Last Usable Host

192.168.1.254

Total Addresses

256

Usable Hosts

254

Spark says

Formula

Network = IP \;\&\; Mask, \quad Broadcast = Network \;|\; \lnot Mask

Mask: — The 32-bit subnet mask derived from the CIDR prefix

What is the IPv4 Subnet Calculator?

Given any IP address and CIDR prefix, this calculator works out the containing subnet's boundaries — the network address (all host bits zero), broadcast address (all host bits one), and the usable range in between.

How to use it

1 Enter an IP address inside the subnet.
2 Enter the CIDR prefix length (the /N in an address like 192.168.1.0/24).

Worked examples

192.168.1.10/24

Network 192.168.1.0, broadcast 192.168.1.255, 254 usable hosts.

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Limitations

•For /31 and /32 subnets, the standard network/broadcast reservation doesn't apply the same way (point-to-point links and single hosts use special conventions) — usable host count is shown as 0 in those cases per the general formula.

Frequently asked questions

What's the difference between this and the CIDR Calculator?

Same underlying math — this one takes the IP address and prefix as separate fields; the CIDR Calculator accepts them combined as a single 'IP/prefix' string, matching how CIDR blocks are usually written.