This subnet calculator takes any IPv4 address and CIDR prefix and works out the full subnet picture: network address, broadcast address, subnet mask, wildcard mask, and the usable host range with its size.
| Network address | – |
|---|---|
| Broadcast address | – |
| Subnet mask | – |
| Wildcard mask | – |
| Usable host range | – |
| Total addresses | – |
| Usable hosts | – |
| IP class / type | – |
How Subnetting Works
An IPv4 address is 32 bits. The CIDR prefix (/26, say) declares the first 26 bits to be the network — shared by every device on the subnet — leaving 6 bits for hosts: 2⁶ = 64 addresses, of which 62 are usable (the first is the network address, the last the broadcast). Subnetting is how one big network gets carved into rooms: departments, VLANs, branches. The bit-level view of all of this is our Binary Converter; this tool sits in our Other Calculators collection.
Worked Example (Verified)
192.168.1.10 /26:
- Subnet mask: 255.255.255.192; wildcard: 0.0.0.63
- Block size 64 → subnets start at .0, .64, .128, .192. Our address sits in the first block:
- Network: 192.168.1.0, usable hosts 192.168.1.1 – 192.168.1.62 (62 hosts), broadcast 192.168.1.63
The CIDR Cheat Sheet
| CIDR | Mask | Hosts | Typical use |
|---|---|---|---|
| /24 | 255.255.255.0 | 254 | Home/small office LAN |
| /25 | 255.255.255.128 | 126 | Splitting a /24 in two |
| /26 | 255.255.255.192 | 62 | Department subnet |
| /27 | 255.255.255.224 | 30 | Small segment / VLAN |
| /28 | 255.255.255.240 | 14 | Server cluster |
| /30 | 255.255.255.252 | 2 | Point-to-point links |
| /16 | 255.255.0.0 | 65,534 | Large campus / cloud VPC |
| /8 | 255.0.0.0 | 16.7 million | 10.0.0.0/8 private space |
Special cases: a /31 (RFC 3021) gives 2 usable addresses with no network/broadcast waste on point-to-point links, and a /32 is a single host route. Private ranges (10/8, 172.16/12, 192.168/16) are flagged in the results.
Related Tools
- Binary Converter — the bits underneath
- Other Calculators — the full collection
Frequently Asked Questions
How many hosts fit in a /26?
62 usable (64 total minus network and broadcast). General rule: usable hosts = 2^(32−CIDR) − 2.
What is a wildcard mask?
The inverse of the subnet mask (0s and 1s flipped): a /26 has wildcard 0.0.0.63. Access-control lists on Cisco gear use wildcard masks to match address ranges.
What is the difference between network and broadcast addresses?
The network address (all host bits 0) names the subnet itself; the broadcast address (all host bits 1) reaches every host on it. Neither is assignable to a device in a normal subnet.
Is 192.168.1.10 a private address?
Yes — 192.168.0.0/16 is RFC 1918 private space, as are 10.0.0.0/8 and 172.16.0.0/12. Private addresses are not routable on the public internet.
How do I split a /24 into 4 subnets?
Borrow 2 bits: /26 gives four subnets of 62 hosts each (.0, .64, .128, .192). Enter each block's address with /26 above to see its full details.
Is this subnet calculator free?
Yes — free, instant, no sign-up. IPv4 only; IPv6 subnetting uses the same prefix logic over 128 bits.