IP Subnet Calculator for IPv4 & IPv6
Calculate subnets in seconds. Enter an IP address and subnet mask (or CIDR prefix) to get the network address, broadcast address, usable host range, subnet mask, wildcard mask, CIDR notation, and IP class.
IPv4 Subnet Calculator
All 1 of the Possible / 24 Networks for 192.168.0
| Network Address | Usable Host Range | Broadcast Address |
|---|---|---|
| 192.168.0.0 | 192.168.0.1 - 192.168.0.254 | 192.168.0.255 |
Understanding Your Results
Every value comes from combining your IP address with your subnet mask. Here's what each field means, using the default example 192.168.0.1 /24:
Network Address
192.168.0.0 — the first address in the subnet; identifies the network itself and can't be assigned to a host.
Broadcast Address
192.168.0.255 — the last address; used to reach every host on the subnet at once.
Usable Host Range
192.168.0.1 – .254 — the addresses you can actually assign to devices.
Subnet Mask
255.255.255.0 — separates the network portion of the address from the host portion.
Wildcard Mask
0.0.0.255 — the inverse of the subnet mask, used in Cisco ACLs and routing rules.
CIDR Notation & Class
/24, Class C, Private — shorthand for the mask plus the legacy class and public/private type.
CIDR / Subnet Mask Cheat Sheet (IPv4)
Match a prefix to its mask and the number of usable hosts it supports.
| CIDR | Subnet mask | Usable hosts |
|---|---|---|
| /8 | 255.0.0.0 | 16,777,214 |
| /12 | 255.240.0.0 | 1,048,574 |
| /16 | 255.255.0.0 | 65,534 |
| /20 | 255.255.240.0 | 4,094 |
| /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 | 0 (point-to-point) |
| /32 | 255.255.255.255 | 0 (single host) |
Usable hosts = 2(host bits) − 2. Full /1–/32 table available on the live page.
Key Subnetting Terms
CIDR Notation
Classless Inter-Domain Routing replaced the old class system. Instead of 255.255.255.0 you write /24 — the first 24 bits are the network. It lets you size a network to any prefix length.
Subnet Mask
A 32-bit value that tells a device which part of an IP address is the network and which is the host. Every host on the same subnet shares the same mask.
Wildcard Mask
The bitwise inverse of the subnet mask (0.0.0.255 for a /24). Used in Cisco ACLs and OSPF: a 0 bit means "must match", a 1 bit means "ignore".
IP Class
The original scheme splitting addresses into Class A (/8), B (/16) and C (/24) by their leading bits. CIDR has largely replaced it, but the class is still reported for reference.
Private vs Public
RFC 1918 ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) can't route on the public internet; everything else is public.
Hosts Per Subnet
Decided by the number of host bits: 2^(host bits) − 2. A /24 gives 254, a /26 gives 62, a /30 gives 2 — see the cheat sheet.
How to Use the IP Subnet Calculator
As simple as that
Provide the base IP address and subnet mask.
Select how you want to divide the network (e.g., number of hosts or subnets).
Instantly see the network address, broadcast address, usable IP range, and more.