IP Subnet Calculator
Calculate IP address subnets, network addresses, broadcast addresses, and usable host ranges. Essential for network administrators.
IP Address Details
Subnet Results
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first address in subnet
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last address in subnet
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first assignable IP
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last assignable IP
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dotted decimal
0
available IPs
💡 Note: The network address and broadcast address cannot be assigned to hosts. Usable hosts = Total hosts - 2.
What is Subnetting?
Subnetting is the process of dividing a large network into smaller, manageable sub-networks (subnets). It improves network performance, security, and organization by logically grouping devices.
IP Address Structure
An IPv4 address consists of 32 bits, divided into 4 octets (8 bits each). It has two parts:
- Network Portion: Identifies the specific network.
- Host Portion: Identifies the specific device on that network.
CIDR Notation
Classless Inter-Domain Routing (CIDR) notation uses a slash followed by the number of network bits. For example, 192.168.1.0/24 means the first 24 bits are the network portion.
Common Subnet Masks
| CIDR | Subnet Mask | Total Hosts | Usable Hosts |
|---|---|---|---|
| /24 | 255.255.255.0 | 256 | 254 |
| /25 | 255.255.255.128 | 128 | 126 |
| /26 | 255.255.255.192 | 64 | 62 |
| /27 | 255.255.255.224 | 32 | 30 |
| /28 | 255.255.255.240 | 16 | 14 |
| /29 | 255.255.255.248 | 8 | 6 |
| /30 | 255.255.255.252 | 4 | 2 |
Private IP Address Ranges
- Class A: 10.0.0.0 – 10.255.255.255 (/8)
- Class B: 172.16.0.0 – 172.31.255.255 (/12)
- Class C: 192.168.0.0 – 192.168.255.255 (/16)
References
- Cisco. "Subnetting Basics." 2026.
- IANA. "IPv4 Address Space Registry." 2026.