Subnet Calculator
Enter an IPv4 address and CIDR (e.g. 192.168.1.10/24) for the full subnet breakdown.
Break down any IPv4 subnet
Subnetting turns one address block into many, and getting the boundaries right is essential for network configuration and firewall rules. Enter an address with its CIDR prefix and this returns every derived value at once.
For 192.168.1.10/24 the network is 192.168.1.0, the broadcast is 192.168.1.255, the mask is 255.255.255.0, and there are 254 usable hosts from .1 to .254. Change the prefix and every figure updates live.
Exact bitwise math, kept local
It works directly on the 32-bit integer form of the address with unsigned bit operations, so the results are exact. Everything is computed in your browser.
Frequently Asked Questions
What does it calculate?
From an address and prefix it derives the network and broadcast addresses, subnet mask, wildcard mask, usable host range, and the number of hosts.
How is the host count found?
A /n subnet has 2^(32−n) addresses; two are reserved for network and broadcast, so usable hosts are 2^(32−n) − 2 (with /31 and /32 handled as special cases).
Is my data sent anywhere?
No. All the bitwise math runs in your browser and nothing you type is uploaded.
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