IP Subnet Calculator
Subnet Details:
Network Address: –
Broadcast Address: –
First Usable Host: –
Last Usable Host: –
Subnet Mask (Dotted Decimal): –
Subnet Mask (CIDR): –
Total Hosts: –
Usable Hosts: –
Understanding IP Subnetting
The IP Subnet Calculator is an essential tool for network administrators, IT professionals, and anyone learning about computer networking. It helps you break down an IP address and its associated subnet mask into critical components, providing a clear understanding of how networks are segmented.
What is an IP Address?
An Internet Protocol (IP) address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. In IPv4, these addresses are 32-bit numbers, typically represented in dotted-decimal notation (e.g., 192.168.1.10), where four numbers (octets) are separated by dots, each ranging from 0 to 255.
The Role of a Subnet Mask
A subnet mask is a 32-bit number that divides an IP address into two parts: the network portion and the host portion. It tells a device which part of an IP address identifies the network and which part identifies the specific device (host) within that network. This division allows for efficient routing of data packets and the creation of smaller, more manageable subnetworks (subnets).
Subnet masks can be expressed in dotted-decimal notation (e.g., 255.255.255.0) or using Classless Inter-Domain Routing (CIDR) notation (e.g., /24). CIDR notation simply indicates the number of bits used for the network portion of the address.
Key Subnet Details Explained
- Network Address: This is the first address in a given subnet. It's used to identify the network itself and cannot be assigned to a host device. All host bits are set to zero.
- Broadcast Address: This is the last address in a given subnet. Packets sent to this address are delivered to all devices within that subnet. All host bits are set to one.
- First Usable Host: This is the first IP address in the subnet that can be assigned to a device. It's always one greater than the Network Address (unless it's a /31 or /32 subnet).
- Last Usable Host: This is the last IP address in the subnet that can be assigned to a device. It's always one less than the Broadcast Address (unless it's a /31 or /32 subnet).
- Total Hosts: The total number of IP addresses available within the subnet, including the network and broadcast addresses. Calculated as 2^(32 – CIDR).
- Usable Hosts: The number of IP addresses within the subnet that can actually be assigned to devices. For most subnets (CIDR < 31), this is Total Hosts – 2 (excluding the network and broadcast addresses). For /31 subnets, there are 2 usable hosts (the network and broadcast addresses themselves are usable for point-to-point links). For /32 subnets, there is 1 usable host (the IP address itself).
How to Use the Calculator
Simply enter an IP Address (e.g., 192.168.1.10) and its corresponding Subnet Mask in CIDR notation (e.g., 24 for 255.255.255.0). Click "Calculate Subnet Details" to instantly retrieve the Network Address, Broadcast Address, range of usable host IPs, and other relevant subnet information.
Example Calculation:
Let's say you have an IP address 172.16.10.50 with a CIDR of /20.
- IP Address:
172.16.10.50 - Subnet Mask (CIDR):
20
The calculator would output:
- Network Address:
172.16.0.0 - Broadcast Address:
172.16.15.255 - First Usable Host:
172.16.0.1 - Last Usable Host:
172.16.15.254 - Subnet Mask (Dotted Decimal):
255.255.240.0 - Subnet Mask (CIDR):
/20 - Total Hosts:
4096 - Usable Hosts:
4094
This means that any device with an IP address from 172.16.0.1 to 172.16.15.254 belongs to this specific subnet.