Free tools
CIDR Subnet Calculator
IPv4 CIDR calculator. Convert IP/CIDR to network address, broadcast, netmask, wildcard mask, and usable host range — in your browser.
IPv4 CIDR
Tip: You can also paste a bare IP like 10.0.0.1 (defaults to /32).
Results
Network
Network address:
Broadcast:
Netmask:
Wildcard:
Hosts
First host:
Last host:
Total addresses:
Usable hosts:
IPv4 CIDR subnet calculator
Paste an IPv4 address and prefix (CIDR notation) like 192.168.1.10/24 to calculate the network address, broadcast address, netmask, wildcard mask, and usable host range. Everything runs locally in your browser.
How to use
- Enter an IPv4 address (optionally with /prefix).
- Click Calculate.
- Copy the summary for documentation or tickets.
What the fields mean
- Network address: the first address in the subnet
- Broadcast: the last address (used for broadcast in most subnets)
- Usable hosts: typically excludes network/broadcast (except /31 and /32)
Common examples
- /24 — 255.255.255.0 (typical LAN)
- /16 — 255.255.0.0
- /32 — single host
Frequently Asked Questions
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation combines an IP address with a suffix indicating the number of network bits. For example, 192.168.1.0/24 means the first 24 bits are the network portion, leaving 8 bits for hosts. It replaced the old Class A/B/C system for more flexible IP allocation.
How do I use the CIDR calculator?
Enter an IP address and CIDR prefix (like 192.168.1.0/24) or an IP with subnet mask (like 192.168.1.0 255.255.255.0). The tool calculates: network address, broadcast address, subnet mask, wildcard mask, total hosts, and usable host range.
What's the difference between total hosts and usable hosts?
Total hosts includes every IP in the range. Usable hosts excludes the network address (first IP) and broadcast address (last IP), which can't be assigned to devices. For a /24 network: 256 total IPs, 254 usable for devices.
What is a wildcard mask?
A wildcard mask is the inverse of a subnet mask. Where a subnet mask has 1s for network bits, the wildcard mask has 0s. It's used in Cisco ACLs (Access Control Lists) and some routing protocols. The tool calculates both for your convenience.
Can I calculate subnets within a larger network?
Yes. Enter a larger CIDR block (like /16) and specify how many subnets you need or what size subnets you want. The tool shows all possible subdivisions, helping with network planning and VLAN assignment.