Subnet Calculator
Calculate network, broadcast, host range and mask for any IPv4 CIDR.
CIDR notation packs a whole network definition into a slash and a number — but turning 192.168.1.130/26 into its actual network address, broadcast, and usable host range requires binary masking that's easy to fumble under pressure during an outage or a firewall change.
Enter any IPv4 address and CIDR prefix (0–32) and this calculator instantly returns the network address, broadcast address, first and last usable host, subnet mask, wildcard mask, and total/usable host counts — including the RFC 3021 special cases for /31 and /32. Everything runs in your browser.
How to use Subnet Calculator
- 1
Enter an IPv4 address
Any address inside the subnet works — it's masked to the network.
- 2
Enter the CIDR prefix
0 to 32, e.g. 24 for a 255.255.255.0 mask.
- 3
Read the full breakdown
Network, broadcast, host range, masks and counts.
Features
- Network, broadcast and usable host range
- Subnet and wildcard masks
- Correct /31 and /32 handling
Frequently asked questions
Common mistakes to avoid
- Confusing a /24 (mask 255.255.255.0) with a /16 or /8 — the prefix counts fixed bits, not octets.
- Assigning the network or broadcast address to a device in subnets larger than /31.
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