Subnet Calculator: Calculate IP Subnets & CIDR | Free Tool

A A subnet divides a network into smaller segments. The CIDR prefix (e.g., /24) determines how many hosts each subnet can have.

A CIDR (Classless Inter-Domain Routing) uses /prefix to indicate the number of network bits. /24 = 256 IPs (254 usable).

A A subnet mask separates the network portion from the host portion of an IP address. /24 = 255.255.255.0.

A Yes.

A Our IP Subnet Calculator simplifies finding the usable host IP range. Simply enter your network's IP address and the CIDR prefix (e.g., 192.168.1.0/24) into the tool. It will instantly display the 'Usable IP Range,' showing the first and last IP addresses available for assigning to devices. This excludes the network address and the broadcast address, crucial for efficient network planning and avoiding configuration errors.

A Our IP Subnet Calculator makes this simple. Enter your network's IP address and the CIDR prefix (e.g., 192.168.1.0/27). The tool instantly displays the 'Host Count,' which represents the total number of IP addresses in that subnet. To find the *usable* IP addresses, subtract two (for the network and broadcast addresses) from this total, giving you the assignable range for your devices.

A The network address identifies the specific subnet itself, and you can't assign it to a device. Similarly, the broadcast address is used to send data to all devices within that subnet, so it's also reserved. Our calculator shows these clearly, for example, with a /24 network like 192.168.1.0/24, the network address is 192.168.1.0 and the broadcast is 192.168.1.255.

A No, this tool only handles IPv4 addresses. IPv6 uses a completely different addressing scheme with 128-bit addresses. For IPv6, you'd need a dedicated IPv6 subnet calculator. A common workaround is to use command-line tools like `ipcalc` or online tools specifically built for IPv6. If you're managing mixed environments, keep both tools bookmarked.

A Two addresses are always reserved: the network ID and the broadcast address. For a /30 subnet, that gives you only 2 usable hosts out of 4 total IPs. Many people forget to subtract these two when planning. If you're configuring a point-to-point link, a /30 is perfect. But for a small office network, a /24 gives you 254 usable addresses. Always check the 'Usable IP Range' field in our calculator before assigning anything.