🌐 IP Subnet Calculator
Type an IPv4 address and choose a CIDR prefix or subnet mask to instantly see the network, broadcast, mask, wildcard, usable host range, and host counts — with /31 and /32 handled correctly.
🌐 Subnet details
| CIDR notation | 192.168.1.0/24 |
|---|---|
| Network address | 192.168.1.0 |
| Broadcast address | 192.168.1.255 |
| Subnet mask | 255.255.255.0 |
| Wildcard mask | 0.0.0.255 |
| First usable host | 192.168.1.1 |
| Last usable host | 192.168.1.254 |
| Total addresses | 256 |
| Usable hosts | 254 |
Subnetting without the binary
Whether you are carving a network into VLANs, chasing an IP conflict, or configuring a firewall rule, the same handful of values keep coming up: which addresses belong to this subnet, which one is the broadcast, and how many hosts fit. This calculator derives them all from a single address and prefix, so you can move from “what network is 172.16.5.130/26 on?” to an answer in one step.
It is a core network-troubleshooting tool — pair it with the Download Time Calculator when you are sizing transfers across those subnets.
❓ Frequently Asked Questions
What does an IP subnet calculator do?
From an IPv4 address plus a prefix length (like /24) or a dotted subnet mask, it works out the network address, the broadcast address, the subnet mask and its wildcard, the first and last usable host addresses, and how many hosts the subnet holds. It is the fastest way to plan or troubleshoot a network without doing binary maths by hand.
How is the number of usable hosts calculated?
Total addresses in a subnet are 2^(32 − prefix). Two are reserved — the network address and the broadcast address — so usable hosts are 2^(32 − prefix) − 2. A /24, for example, has 256 total and 254 usable. The special cases are /31 (RFC 3021 point-to-point, both addresses usable) and /32 (a single host route).
What is the difference between the subnet mask and the wildcard mask?
The subnet mask marks the network bits with 1s (e.g. 255.255.255.0 for /24). The wildcard mask is its bitwise inverse (0.0.0.255) and marks the host bits — it is what access-control lists and routing rules on Cisco-style gear use to match a range of addresses.
Can I trust these results for production network design?
The maths is exact for IPv4, but these are general estimates for planning and learning — always confirm against your actual gear, addressing plan, and any reserved ranges before you deploy. Double-check overlapping subnets and gateway addresses in your specific environment.