Subnet Calculator
Calculate IPv4 subnet details fast, from network and broadcast addresses to host ranges, masks, wildcard masks, and VLSM subnet layouts.
Leave the prefix blank to derive it from the mask automatically.
Network Address
192.168.1.0
Broadcast Address
192.168.1.255
First Usable Host
192.168.1.1
Last Usable Host
192.168.1.254
Usable Hosts
254
Subnet Mask
255.255.255.0
Wildcard Mask
0.0.0.255
IP Class
Class C
CIDR
/24
Binary Representation
11000000 . 10101000 . 00000001 . 00011001
Common CIDR Reference
Quick lookup table for IPv4 subnet masks and usable host counts.
| CIDR | Subnet Mask | Usable Hosts |
|---|---|---|
| /8 | 255.0.0.0 | 16,777,214 |
| /9 | 255.128.0.0 | 8,388,606 |
| /10 | 255.192.0.0 | 4,194,302 |
| /11 | 255.224.0.0 | 2,097,150 |
| /12 | 255.240.0.0 | 1,048,574 |
| /13 | 255.248.0.0 | 524,286 |
| /14 | 255.252.0.0 | 262,142 |
| /15 | 255.254.0.0 | 131,070 |
| /16 | 255.255.0.0 | 65,534 |
| /17 | 255.255.128.0 | 32,766 |
| /18 | 255.255.192.0 | 16,382 |
| /19 | 255.255.224.0 | 8,190 |
| /20 | 255.255.240.0 | 4,094 |
| /21 | 255.255.248.0 | 2,046 |
| /22 | 255.255.252.0 | 1,022 |
| /23 | 255.255.254.0 | 510 |
| /24 | 255.255.255.0 | 254 |
| /25 | 255.255.255.128 | 126 |
| /26 | 255.255.255.192 | 62 |
| /27 | 255.255.255.224 | 30 |
| /28 | 255.255.255.240 | 14 |
| /29 | 255.255.255.248 | 6 |
| /30 | 255.255.255.252 | 2 |
| /31 | 255.255.255.254 | 2 |
| /32 | 255.255.255.255 | 1 |
How to Use
- Enter an IPv4 address and either a CIDR prefix like /24 or a subnet mask like 255.255.255.0.
- Review the calculated network address, broadcast address, usable host range, wildcard mask, and binary representation.
- Switch to VLSM / Subnet Divider to split a larger network into equal-size subnets or allocate different host counts per subnet.
- Use the CIDR reference table to compare common prefixes, masks, and host capacities before designing your network.
Frequently Asked Questions
What does CIDR mean?
CIDR stands for Classless Inter-Domain Routing. It uses a slash notation like /24 to show how many bits belong to the network portion of an IPv4 address, which makes subnetting more flexible than older class-based addressing.
What is the difference between a subnet mask and a wildcard mask?
A subnet mask marks the network bits with 1s and the host bits with 0s. A wildcard mask is the inverse, with network bits as 0s and host bits as 1s. Wildcard masks are often used in routing and ACL configurations.
How many usable hosts are in a subnet?
For most IPv4 subnets, usable hosts equal total addresses minus 2, because one address is the network address and one is the broadcast address. Special cases include /31 point-to-point networks and /32 single-host routes.
What is VLSM?
VLSM stands for Variable Length Subnet Masking. It lets you create subnets of different sizes inside the same parent network, so you can avoid wasting IP space and match each subnet to the number of hosts it actually needs.