Subnet / CIDR Calculator
Enter an IPv4 CIDR block to instantly get the network and broadcast addresses, usable host range, host counts, netmask and wildcard mask.
Subnet /24
- Network address
- 192.168.1.0
- Broadcast address
- 192.168.1.255
- Netmask
- 255.255.255.0
- Wildcard mask
- 0.0.0.255
- Usable host range
- 192.168.1.1 – 192.168.1.254
- Total addresses
- 256
- Usable hosts
- 254
- Type
- Private (RFC 1918)
Calculated instantly in your browser — no data leaves your device.
What is a subnet calculator?
Subnetting splits an IP network into smaller blocks. Getting the boundaries right by hand means fiddling with binary masks — easy to get wrong. This calculator takes a CIDR block like 10.0.0.0/8 and works out everything you need: the network and broadcast addresses, the first and last usable host, how many addresses the block contains, and the netmask and wildcard mask (handy for ACLs and firewall rules). It all runs in your browser.
Common uses
- Planning VPC / VLAN address space without overlaps.
- Writing firewall and router ACL rules using wildcard masks.
- Sizing a subnet to fit a required number of hosts.
- Sanity-checking whether an IP falls inside a given block.
How to use it
- 1Type a CIDR block such as 192.168.1.0/24.
- 2Or tap a preset for a common private range.
- 3Read the network, broadcast and usable host range.
- 4Copy the netmask or wildcard mask for your config.
Frequently asked questions
What is CIDR notation?+
CIDR (Classless Inter-Domain Routing) notation writes a network as an address plus a prefix length, like 192.168.1.0/24. The /24 means the first 24 bits are the network portion, leaving 8 bits for hosts.
How many usable hosts are in a /24?+
A /24 has 256 total addresses, but the network and broadcast addresses are reserved, leaving 254 usable host addresses. This calculator shows both totals for any prefix.
What are the network and broadcast addresses?+
The network address is the first address in the block (all host bits 0) and identifies the subnet itself. The broadcast address is the last (all host bits 1) and reaches every host on the subnet. Neither is assignable to a device.
What's the difference between /30 and /31?+
A /30 gives 2 usable hosts (4 total minus network and broadcast) and is classic for point-to-point links. A /31 (RFC 3021) repurposes both addresses as usable, giving exactly 2 hosts with no waste — also common on point-to-point links.