Network and IP address calculator

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IP/Netmask: (input format examples: or

Usable addresses:
Mask: =
Mask as hex:
First usable:
Last usable:

Converters for Network and IP address

Subnet netmask dotted decimal to CIDR notation (bits format)

result: /

Class C subnet calculator

number of subnets to create:


mask: / dotted dec. mask:
amount of usable host addresses per subnet:
addresses in each subnet:

Number of required addresses to netmask

number of host addresses needed:


mask: / dotted dec. mask:
usable amount of addresses:

Dotted decimal IP-address or mask to binary and hex



Hex IP-address or mask to dotted decimal


dotted decimal:

IP-address bit-complement (inverted IP) calculator


Network Mask to amount of usable addresses

Mask: /


Usable amount of addr: Total number of addr:
Netmaks in dotted decimal format:

Number converter: decimal => bin, hex




Number converter: binary => dec, hex




Number converter: Hex => dec, bin




IP Multicast addresses (

All multicast addresses can easily be recognized because they start with the bit pattern "1110". - Link-local scope multicast address - Globally-scoped (Internet-wide) multicast addresses - Local multicast addresses
Well known multicast addresses are listed at

Multicast addresses use a destination Mac-address in the range from
01:00:5E:00:00:00 to 01:00:5E:7F:FF:FF
The IP address maps directly to a Mac address. The lower 23 Bits of the multicast IPv4 Address are added to the lower 23 Bits of the Mac address. Example: would be send to the Mac address 01:00:5E:00:00:D2.
Ethernet frames with a value of 1 in the least-significant bit of the first octet of the destination address (logical AND with 01:00:00:00:00:00) are sent to all ports on the same switch unless the switch is VLAN aware and there is a VLAN tag between ethernet and IP layer. In other words the Ethernet address and the VLAN tag define together to which ports a packets is sent.

Special and private address ranges

Private address ranges are not routed on the Internet and can be freely allocated in any private network. NAT (network address translation) is required when connecting such a network to the Internet.

Private network addresses (RFC1597/RFC1918 addresses): - A 24-bit block, /8, class A network - A 20-bit block, /12, set of 16 contiguous class B network numbers - A 16-bit block, /16, set of 255 contiguous class C network numbers

Special addresses: - Special address range for the localhost. You can normally not use those addresses for anything else. is generally assigned to the loopback device Special host address commonly reserved for the default route

Overview of common subnets and masks

Mask Hosts  Usable Netmask          Hex Mask
/30  4      2  fffffffc  this is 1/64 of a Class C net
/29  8      6  fffffff8  this is 1/32 of a Class C net
/28  16     14  fffffff0  this is 1/16 of a Class C net
/27  32     30  ffffffe0  this is 1/8 of a Class C net
/26  64     62  ffffffc0  this is 1/4 of a Class C net
/24  256    254    ffffff00  this is a Class C net
/23  512    510    fffffe00  these are 2 Class C net
/22  1024   1022    fffffc00  these are 4 Class C net
/21  2048   2046    fffff800  these are 8 Class C net
/20  4096   4094    fffff000  these are 16 Class C net
/19  8192   8190    ffffe000  these are 32 Class C net
/18  16384  16382    ffffc000  these are 64 Class C net
/17  32768  32766    ffff8000  these are 128 Class C net
/16  65536  65534      ffff0000  these are 256 Class C net = Class B net

© Guido Socher, version 2016-01-23
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