IP Subnet Calculator

IP Subnet Calculator

IP Terminology

Address: The unique ID that is assigned to one interface.

Subnet: A part of a network that shares a specific subnet address.

Subnet mask:  The subnet mask specifies the portion of the address, which refers to the subnet and the part that refers to the host (32-bit).

Interface: This is a network connection.

virot's javaScript IP Calculator

Input

IP-Address: Subnet:

Output

IP Address:First usable:
Subnet:Last usable:
CIDR:Amount of usable:
Network address:Reverse address:
Broadcast address:Unused:
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Mask Class

Class A: 255.0.0.0
Class B: 255.255.0.0
Class C: 255.255.255.0

What is an IP Address?

To identify a device uniquely, we assign it an IP address, which is 32 binary bits.  There are two portions of an IP address: the network portion and the host portion. Note the IP address is divided into 4 octets (1 octet = 8 bits). Every part (e.g., octet) is converted to a decimal and separated by a dot. The value in each octet ranges from 0 to 255. In a network, there are 5 classes: A, B, C, D, and E.

When a device has an IP address, the class of the IP address is determined from the three high-order bits, which is shown in the figure at Cisco Systems. Visit http://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/13788-3.html

In order to facilitate the management of a network, especially a large network, it is best to subdivide it using a process called subnetting. The best way to understand subnetting is by using the telephone network as an example. Any telephone can be used to call another telephone, but area codes identify the region within which a telephone is located. The three-digit area code can be seen as a subnet within the greater network.

Static subnetting

CIDRSubnet maskBinaryAddressesUsable hosts
/1128.0.0.010000000.00000000.00000000.0000000021474836482147483646
/2192.0.0.011000000.00000000.00000000.0000000010737418241073741822
/3224.0.0.011100000.00000000.00000000.00000000536870912536870910
/4240.0.0.011110000.00000000.00000000.00000000268435456268435454
/5248.0.0.011111000.00000000.00000000.00000000134217728134217726
/6252.0.0.011111100.00000000.00000000.000000006710886467108862
/7254.0.0.011111110.00000000.00000000.000000003355443233554430
/8255.0.0.011111111.00000000.00000000.000000001677721616777214
/9255.128.0.011111111.10000000.00000000.0000000083886088388606
/10255.192.0.011111111.11000000.00000000.0000000041943044194302
/11255.224.0.011111111.11100000.00000000.0000000020971522097150
/12255.240.0.011111111.11110000.00000000.0000000010485761048574
/13255.248.0.011111111.11111000.00000000.00000000524288524286
/14255.252.0.011111111.11111100.00000000.00000000262144262142
/15255.254.0.011111111.11111110.00000000.00000000131072131070
/16255.255.0.011111111.11111111.00000000.000000006553665534
/17255.255.128.011111111.11111111.10000000.000000003276832766
/18255.255.192.011111111.11111111.11000000.000000001638416382
/19255.255.224.011111111.11111111.11100000.0000000081928190
/20255.255.240.011111111.11111111.11110000.0000000040964094
/21255.255.248.011111111.11111111.11111000.0000000020482046
/22255.255.252.011111111.11111111.11111100.0000000010241022
/23255.255.254.011111111.11111111.11111110.00000000512510
/24255.255.255.011111111.11111111.11111111.00000000256254
/25255.255.255.12811111111.11111111.11111111.10000000128126
/26255.255.255.19211111111.11111111.11111111.110000006462
/27255.255.255.22411111111.11111111.11111111.111000003230
/28255.255.255.24011111111.11111111.11111111.111100001614
/29255.255.255.24811111111.11111111.11111111.1111100086
/30255.255.255.25211111111.11111111.11111111.1111110042
/31255.255.255.25411111111.11111111.11111111.1111111020
/32255.255.255.25511111111.11111111.11111111.1111111110

IPv6 blocksizes

CIDRDescriptionNumber of /64
/32Default blocksize for a LIR4,294,967,2961677721616777214
/48Default block for companies65,53621474836482147483646
/53192.0.0.025610737418241073741822
/64Default block1536870912536870910
/128Only one device1/4,294,967,296268435456268435454