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IP Subnet Calculator

CIDR Netmask tool generates a list of IP Address Ranges that falls inside a given netmask along with an IP. Just enter IPv4 or IPv6 address along with a netmask or CIDR, and submit to generate the list of network IPs and the list of IPs that falls inside the given input range.

Block Details Results
Block Size 256
Broad Cast
First IP
Last IP
PrefixLength 24
Network List
IP List

About IP Subnet Calculator - Subnet Mask Calculator

CIDR Netmask tool generates a list of IP Address Ranges that falls inside a given netmask along with an IP. Enter IPv4 or IPv6 address and a netmask or CIDR and submit to generate the list of network IPs and host IPs that fall inside the given input range.

What do you mean by subnetting?

Subnetting means breaking down a single network into smaller networks, called subnets or sub-networks. That technique was initially created to solve the shortage of IP addresses. But since its presence, it becomes an efficient management practice for IP network utilization.

An IP address comprises three significant classes, Class A, Class B, and Class C. 

  • Class A with over 16 million IP addresses.
  • Class B with 65,535 IP addresses.
  • Class C with 254 IP addresses.

Without the subnetting; you would only use one network from each class. Suppose you require 150 addresses, then you need the license of Class C. Even after utilizing 150 addresses, you have 104 addresses that would remain unused.

Subnetting facilitates the network administrators to take some bits from the host part of an IP address and use these bits to create smaller networks inside the leading network. These smaller networks comprise several IP addresses, sharing the same IP routing prefix used by the original IP address to design the subnets. Once you created these smaller networks, you can build a network of interconnecting subnetworks to divide your network's load more effectively.

It's important for network administrators, especially in large enterprises, to subnet their network because reorganizing the network in such a way makes the IP network utilization more efficient.

What is a subnet mask?

When designing a network, it's good to balance the network and the host part of an IP address to avoid 

  • too many networks to route to 
  • and too few hosts in a network

A subnet mask is a 32-bit number that determines the potential range of IP addresses in a network. Each subnet mask defines how many IP addresses can be on a single network, and you can use the multiple subnet masks to organize an entire network into sub-subnets.

A subnet mask splits the IP address into the host and network parts, thus defining which part belongs to the network and the device.

A device is a default gateway that connects the local devices to other networks. Suppose a local device wants to send information to a device at an IP address on another network. It first sends its packets to the default gateway, then forwards the data to another network's IP address.

To find which part is a host and which part is a subnet, you must convert both numbers into binary. Any address bits that correspond to 1 in the IP class's default mask represent the subnet, and any address bits that correspond to a 0 in the default mask represent the host. 

For example, an IP address ( is subnetted into a network address ( and a host address (, utilizing a subnet mask of

IP address 11000000.00000000.00000010.10000010
Subnet mask 11111111.11111111.11111111.11000000
Network prefix 11000000.00000000.00000010.10000000
Host part 00000000.00000000.00000000.00000010

What's the difference between subnetting and CIDR?

CIDR is based on the concept called subnetting. CIDR and subnetting are practically the same thing. Subnetting is usually used within an organization or internal networking, and CIDR is often used by ISP's. Once blocks of IP addresses are allocated to end-users, CIDR enables them to be further divided within a private network, a process known as subnetting. 

For example, suppose you have a subnet mask of, equivalent to a /24 network prefix. If you transform the subnet mask to its binary number form, you will see that the first 24 bits are set to one (11111111.11111111.11111111.00000000). 

When you start subnetting an existing block of IPs, you start with the provided subnet mask and move towards the right until you have the required number of subnets needed for your network. For example, suppose your provider has provided you the following network address: And you need to break this network into six separate subnets. If we use a /27 network prefix (subnet mask), we will have a total of 8 subnets at our disposal, each with 32 IPs.

What is the purpose of subnetting?

You have to subnet your network because of the following principal reasons.

  • Subnetting helps in partitioning the large enterprise network into smaller networks as per the resources. Suppose if you divide the network into subnetworks as per the department basis. Then you will quickly identify which department is facing the problem by looking at the IP. And it's become easy for you to troubleshoot that problem. 
  • An un-subnetted network can compromise your network security in several ways. Suppose all devices are using the same subnet. Then there may be a chance that a server with sensitive and confidential information may be exposed to any employee. Or some cyber-hacker can get access to that information and critical systems hosted on the subnet by gaining access to an employee workstation. 
  • Subnetting helps in the better utilization of IP networks. The technique was designed because creating and setting aside the million IP addresses was a waste of time and effort. Increasing the range of your IP addresses by building subnets enables you to scale and makes your network more operative. If you have too many subnet masks, modifying the subnet's size by adjusting the subnet mask will free up more IP addresses for other subnets. 

What does a subnet calculator do?

A subnet calculator is a tool that IT professionals and network administrators use to instantly and precisely calculate subnets on a network.

It's a helpful tool for determining the number of possible subnets for any given network address block.

You can manually divide a large network and allocate IP address ranges to different teams. But, it's better that you have an online tool to cross-check your subnet calculations before final configuration in the router.

IP Subnet Calculator tool divides a given IPv4 or IPv6 address network into the subnetworks by calculating helpful information like a Netmask, CIDR, Block size, Broadcast address, First IP, and Last IP, Network address, Prefix length, and Cisco wildcard mask. 

You have to enter the IP Address and Subnet Mask, and this tool instantly calculates the required information for your use.