Networking
Subnet Calculator
Type an IPv4 address plus CIDR prefix to instantly see the network and broadcast addresses, usable host range, wildcard mask, and classful designation.
Break down IPv4 network, broadcast, host counts, and masks from CIDR notation.
Binary mask
11111111.11111111.11111111.00000000
CIDR fundamentals
Network = IP AND subnet mask. Broadcast = network OR wildcard. Usable hosts = 2^(32 − CIDR) − 2 (except /31 and /32, which are treated specially).
How to use
- Enter an IPv4 address such as 192.168.1.42 and set the CIDR prefix (0–32).
- Review the derived subnet mask, wildcard mask, network, and broadcast addresses.
- Copy the usable host range and capacity to plan VLANs, lab exercises, or certification homework.
Example
Input: IP = 192.168.1.42/26
Output: Network = 192.168.1.0, Broadcast = 192.168.1.63, Usable hosts = 62 (192.168.1.1–192.168.1.62)
FAQ & notes
Does it support /31 or /32 links?
Yes. /31 shows the two point-to-point addresses as usable, while /32 reserves the single host without a broadcast address.
What about IPv6?
This tool focuses on IPv4 subnetting today. IPv6 planning is on the roadmap as a separate calculator.