🌐 IP Subnet Calculator
Enter any IPv4 address with a prefix (/24) or mask (255.255.255.0) and get the network, broadcast, usable range and host count — plus an equal-split subnet plan.
| CIDR notation | 192.168.1.0/24 |
|---|---|
| Network address | 192.168.1.0 |
| Broadcast address | 192.168.1.255 |
| Usable host range | 192.168.1.1 – 192.168.1.254 |
| Usable hosts | 254 |
| Subnet mask | 255.255.255.0 |
| Wildcard mask | 0.0.0.255 |
| Mask in binary | 11111111.11111111.11111111.00000000 |
| IP in binary | 11000000.10101000.00000001.00001010 |
| Address class | C |
| Scope | Private (RFC 1918) |
All subnet math runs in your browser — addresses and network plans are never uploaded.
How the ip subnet calculator works
A subnet mask divides an IP address into a network part and a host part. The calculator applies the mask with bitwise AND to find the network address, sets all host bits to 1 for the broadcast address, and the usable hosts are everything in between (2^host-bits − 2, since network and broadcast addresses are reserved). It also shows the wildcard mask (the inverted mask, used in Cisco ACLs), the binary form so you can see where the boundary falls, the address class and whether the address is private (RFC 1918), and can split the network into equal smaller subnets for addressing plans. Your addressing plan never leaves the browser — relevant, since internal IP layouts are exactly the kind of information not to paste into random websites.
Two special cases trip people up: a /31 has no broadcast address — RFC 3021 allows both addresses to be used on point-to-point links — and a /32 is a single host route. Also remember the "subtract 2" rule applies per subnet, not per network: splitting a /24 into four /26s gives 4 × 62 = 248 usable hosts, not 254.
Frequently asked questions
How many usable hosts are in a /24?
A /24 has 256 addresses, of which 254 are usable — one is the network address and one the broadcast. The general rule is 2^(32 − prefix) − 2.
What is a wildcard mask?
The bitwise inverse of the subnet mask — /24’s mask 255.255.255.0 has wildcard 0.0.0.255. Cisco access-control lists and OSPF configuration match addresses using wildcards rather than masks.
What does the /26 style notation mean?
CIDR prefix notation: the number counts the leading 1-bits in the mask. /26 means 26 network bits, i.e. mask 255.255.255.192, leaving 6 host bits (62 usable hosts).
Which IPv4 ranges are private?
RFC 1918 reserves 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 for private networks. The calculator flags these, plus loopback (127/8), link-local (169.254/16) and carrier-grade NAT (100.64/10).
Why do /31 subnets show 2 usable hosts?
RFC 3021 permits both addresses of a /31 on point-to-point links (router-to-router), where no broadcast is needed. Most vendors support it; it halves address consumption on links.
Is my IP or network plan uploaded?
No — all the bit math happens in your browser. Nothing you type is sent anywhere, which matters when you’re planning internal address space.