Automatic Subnet Calculator

Enter Your Original CIDR:

Choose one of the following automated calculation methods:

Specify new subnet mask

Specify number of subnets needed

Specify number of hosts needed per subnet

New Subnet Mask:

Select columns to display:

Network

Netmask

Network Bits

Host Bits

Hosts

Borrowed Bits

Range

Usable IPs

Subnet Name

Want to manually split one by one? Go here: Manual Subnet Calculator It allows you to manually split or join.

Notes:

Network Bits = Derived from CIDR notation /n
Host Bits = Total bits (32) - network bits
Number of Hosts = 2^{Host bits} - 2
Borrowed bits = New Subnet's network bits - Original vnet's network bits
Number of Subnets = 2^{Borrowed bits}

Subnet Reference table for different network classes

Class A

[0.0.0.0 - 127.255.255.255]

Network Bits: 8, Host Bits: 24

Network Bits	Subnets	Hosts (per subnet)	Subnet Mask

Class B

[128.0.0.0 - 191.255.255.255]

Network Bits: 16, Host Bits: 16

Network Bits	Subnets	Hosts (per subnet)	Subnet Mask

Class C

[192.0.0.0 - 223.255.255.255]

Network Bits: 24, Host Bits: 8

Network Bits	Subnets	Hosts (per subnet)	Subnet Mask