IP Subnet Calculator
Calculate network details, IP ranges, and usable hosts from an IPv4 or IPv6 address and CIDR mask.
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Quick Tip
The most common subnet masks are /24 for home networks (255.255.255.0) and /32 for single hosts.
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Enter an IP address and select a CIDR prefix to see detailed network information.
Related Tools
View AllUnderstanding IP Subnetting
Subnetting is the practice of dividing a network into two or more smaller networks. It increases routing efficiency, enhances network security, and reduces broadcast domain size.
IPv4: An address consists of 32 bits, divided into a **Network ID** and a **Host ID**. The **Subnet Mask** (e.g., 255.255.255.0) determines where the split occurs.
IPv6: An address consists of 128 bits. Subnetting is simpler because there is no variable-length subnet mask in the same way as IPv4. Instead, a **Prefix Length** (e.g., `/64`) is used to denote the network portion. Standard subnetting in IPv6 almost always uses a `/64` prefix for end-user networks.
Common IPv4 CIDR Reference
| CIDR | Subnet Mask | Total Hosts |
|---|---|---|
| /32 | 255.255.255.255 | 1 (Single Host) |
| /30 | 255.255.255.252 | 4 (2 Usable) |
| /24 | 255.255.255.0 | 256 (254 Usable) |
| /16 | 255.255.0.0 | 65,536 (65,534 Usable) |
| /8 | 255.0.0.0 | 16.7 Million |
Common IPv6 Prefixes
| Prefix | Typical Usage | Address Count |
|---|---|---|
| /128 | Single Host (Loopback, etc.) | 1 |
| /64 | Standard LAN Subnet | 18 Quintillion (2^64) |
| /56 | Typical Home/Small Business Assignment | 256 x /64 Subnets |
| /48 | Large Organization Assignment | 65,536 x /64 Subnets |
| /32 | ISP Allocation | 4 Billion x /64 Subnets |