IPv4 Subnet Calculator
Enter an IP and CIDR prefix to get the network address, broadcast, host range, and subnet mask.
| Network address | 192.168.1.0/24 |
| Subnet mask | 255.255.255.0 |
| Wildcard mask | 0.0.0.255 |
| Broadcast address | 192.168.1.255 |
| First usable host | 192.168.1.1 |
| Last usable host | 192.168.1.254 |
| Total addresses | 256 |
| Usable hosts | 254 |
| Class | C |
| Range type | Private (RFC 1918) |
About the IPv4 Subnet Calculator
CIDR notation packs a whole network definition into one short string: 192.168.1.0/24 means the first 24 bits identify the network and the rest identify hosts within it. This calculator unpacks that into everything you actually need when configuring networks, firewalls, VPCs, and Kubernetes clusters: the network and broadcast addresses, the usable host range, the subnet mask in dotted form, and how many hosts fit.
Drag the prefix slider to see how the math changes: each bit added to the prefix halves the number of hosts. A /24 holds 254 usable hosts, a /16 holds 65,534, and a /30 (common for point to point links) holds just 2.
The calculator also identifies private RFC 1918 ranges (10.x.x.x, 172.16-31.x.x, 192.168.x.x), which is a quick way to confirm whether an address in a log or config is internal or routable on the public internet. Everything runs in your browser.
Reach developers and designers who use these tools every day. Privacy-first, no trackers.
Frequently asked questions
Why are two addresses unusable in each subnet?
The all-zeros host address is the network identifier and the all-ones address is the broadcast address. Neither can be assigned to a device. The exceptions are /31 (point to point links, both addresses usable) and /32 (a single host route).
What is a wildcard mask?
The bitwise inverse of the subnet mask, used by Cisco ACLs and OSPF configuration. Where the subnet mask for /24 is 255.255.255.0, the wildcard is 0.0.0.255.
Which private range should I use for my network?
10.0.0.0/8 gives the most room and is the common choice for cloud VPCs. 192.168.0.0/16 is the home router default. The main rule: pick ranges that will not collide if networks ever need to be connected or peered.
Do IP classes still matter?
Not for routing, which has been classless (CIDR) since 1993. Classes survive as vocabulary: people still say "class C" to mean a /24. The calculator shows the class for that historical reference only.