IPv4 Subnet Calculator
/32 (Host)
/31
/30
/29
/28
/27
/26
/25
/24 (Class C)
/23
/22
/21
/20
/19
/18
/17
/16 (Class B)
/15
/14
/13
/12
/11
/10
/9
/8 (Class A)
/7
/6
/5
/4
/3
/2
/1
Network Address
Subnet Mask
Broadcast Address
Usable Host Range
Total Hosts
Usable Hosts
Wildcard Mask
CIDR Notation
Understanding Subnetting and IP Addressing
Subnetting is the practice of dividing a physical network into smaller, logical sub-networks. This process is essential for managing network traffic, enhancing security, and optimizing the utilization of limited IPv4 address space. By using a subnetting calculator, network engineers can quickly determine the boundaries of a network without performing complex binary arithmetic manually.
Key Subnetting Terms
- IP Address: A 32-bit numerical label assigned to each device participating in a computer network that uses the Internet Protocol.
- Subnet Mask: A 32-bit number that masks an IP address and divides the IP address into network address and host address parts.
- CIDR (Classless Inter-Domain Routing): A method for allocating IP addresses and IP routing that replaces the older system based on classes (Class A, B, and C). It uses a "/" notation followed by the number of bits in the mask.
- Network Address: The first address in a subnet, used to identify the network itself. It cannot be assigned to a host.
- Broadcast Address: The last address in a subnet, used to communicate with all hosts on that subnet simultaneously.
Example Calculation:
If you have an IP of 192.168.1.10 with a /24 prefix:
– The Subnet Mask is 255.255.255.0.
– The Network ID is 192.168.1.0.
– The Broadcast is 192.168.1.255.
– You have 254 usable host addresses (192.168.1.1 to 192.168.1.254).
If you have an IP of 192.168.1.10 with a /24 prefix:
– The Subnet Mask is 255.255.255.0.
– The Network ID is 192.168.1.0.
– The Broadcast is 192.168.1.255.
– You have 254 usable host addresses (192.168.1.1 to 192.168.1.254).
Why use a Subnet Calculator?
Manual subnetting involves converting decimal octets into 8-bit binary strings, applying logical AND operations with the mask, and converting back. This is prone to human error, especially when working with non-standard prefixes like /27 or /19. Our calculator automates this logic, providing instant results for network planning and troubleshooting.