How many usable hosts per /24?

254 usable hosts (256 total minus network and broadcast).

What is a wildcard mask?

It’s the inverse of the subnet mask, common in ACLs and some router configs.

Subnet/CIDR Calculator

Subnet/CIDR Calculator (IPv4)

Type a CIDR (e.g., 192.168.1.10/24) or IP and mask.

CIDR

IP Address

Mask length

Result

Network: -
Netmask: - (- wildcard)
Broadcast: -
First Host: -
Last Host: -
Total Hosts: -

Make IPv4 Subnetting Less Error‑Prone

Calculate network, broadcast, host range, and usable hosts from a CIDR or IP/mask quickly. It’s a lightweight helper for network planning, lab setups, and exam practice.

What You Can Check

Network and broadcast addresses for a given CIDR.
Wildcard mask and dotted‑decimal netmask equivalents.
First and last usable host addresses and total host count.

Tips

Remember that /31 and /32 have special semantics for point‑to‑point and hosts.
Document subnets alongside VLANs to avoid overlap and confusion.