⭐ 0
🔍
Text Image PDF & Docs Audio Music Electronics Time Utilities Validators Esoteric Games

Subnet Calculator

Calculate the network address, broadcast, subnet and wildcard masks, host range and usable host count for any IPv4 address and CIDR prefix.

Processing... 0%
Parsing IPv4 address
Applying subnet mask
Computing host range
Done

Result

Subnetting questions appear everywhere — configuring a router, sizing a VLAN, writing a firewall rule, studying for a networking exam — and they all reduce to the same bit arithmetic: apply the mask, find the network, find the broadcast, count what is left in between. This calculator does exactly that for any IPv4 address and any CIDR prefix from /8 to /30, returning the network address, broadcast address, subnet mask, wildcard mask, the first and last usable host and both address counts in one pass.

The math is transparent rather than magical. A prefix /p means p network bits, so the subnet mask is p ones followed by zeros, the wildcard mask is its bitwise inverse, the network address is IP AND mask, and the broadcast is the network OR wildcard. The remaining 32 − p host bits give 2^(32−p) total addresses, of which 2^(32−p) − 2 are usable because the all-zeros and all-ones combinations are reserved. A /24 therefore holds 254 hosts, a /16 holds 65,534, and a /30 exactly 2 — the point-to-point classic.

Beyond the numbers you also get context: a class note explains what the first octet of your address implies — the historical class A/B/C boundaries that pre-CIDR equipment assumed, the 127.0.0.0/8 loopback block and other reserved ranges. Preset pages cover the prefixes people actually search for: /24 for LANs, /16 for large private networks and /30 for router links.

Like every tool on this site, the subnet calculator runs entirely in your browser using 32-bit integer operations — no server call, no logging of your network layout, and full offline operation once the page is open. Copy the complete result summary with one click and paste it straight into documentation or a ticket.

🛡️
Executed in Browser

Your files and inputs never leave this device. Processing runs completely offline. 100% Secure.

Accepted Formats & Rules

  • Network address, broadcast address, subnet mask and wildcard mask for any IPv4/CIDR pair.
  • First and last usable host plus usable-host and total-address counts (2^(32−p) − 2 arithmetic).
  • IP class note for the entered address and a one-click copy of the full result summary.

Key Benefits

✓ One input pair — IP address and prefix — returns everything at once: network, broadcast, both masks, host range and address counts.
✓ Pure 32-bit integer math computed locally in your browser: no server round-trip, no lookup tables, correct for every prefix from /8 to /30.
✓ The IP class note explains what the first octet implies — classful history, loopback and reserved ranges — so the numbers come with context.

Use Cases

  • • Size a VLAN or office LAN: check how many usable hosts a /23 or /24 really gives before assigning the range.
  • • Fill in firewall or ACL rules with the exact network address, wildcard mask and broadcast for any IP/prefix pair.
  • • Practice CIDR arithmetic for networking exams by verifying your hand-calculated masks, ranges and host counts.