IPv4 Subnet Calculator
Network address, broadcast, host range, wildcard mask and binary breakdown for any IPv4 CIDR block.
Results for 198.51.100.0/28
- Network address
- 198.51.100.0
- Broadcast address
- 198.51.100.15
- Subnet mask
- 255.255.255.240
- Wildcard mask
- 0.0.0.15
- Total addresses
- 16
- Usable hosts
- 14 (excludes network & broadcast)
- First usable host
- 198.51.100.1
- Last usable host
- 198.51.100.14
- CIDR notation
- 198.51.100.0/28
- IP type
- Documentation (TEST-NET-2) (RFC 5737)
How the bits line up
| Octets (binary) | ||||
|---|---|---|---|---|
| IP address | 11000110 | 00110011 | 01100100 | 00000000 |
| Subnet mask | 11111111 | 11111111 | 11111111 | 11110000 |
| Network | 11000110 | 00110011 | 01100100 | 00000000 |
| Broadcast | 11000110 | 00110011 | 01100100 | 00001111 |
The mask's 28 leading ones select the network portion; the remaining 4 bits are available for hosts.
How to use the calculator
Type any block in CIDR notation — 10.0.0.0/22 — or supply an address with a dotted mask, e.g. 10.0.0.5 255.255.255.192. The calculator accepts either form and derives the containing network from whichever host address you give it. Each field in the results panel means:
- Network address — the first address of the block, where the subnet begins.
- Broadcast address — the last address, delivered to every host on the segment.
- First / last usable host — the assignable range between those two endpoints.
- Wildcard mask — the inverted subnet mask used in Cisco ACLs and OSPF match statements.
- Binary breakdown — shows how the mask's leading ones divide network bits from host bits.
Worked example: enter 192.168.1.0/24. With 24 network bits the mask is 255.255.255.0, the network address is 192.168.1.0, broadcast is 192.168.1.255, and hosts may claim 192.168.1.1 through 192.168.1.254 — 254 usable addresses. The result link encodes your query in the URL, so sharing it reopens the identical calculation.
Keep exploring
See every fact about the /28 subnet mask, plan multiple subnets with the VLSM calculator, or convert ranges on the range-to-CIDR tool.