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Subnet Calculator

The number of available network and host addresses are derived from the number of bits used for subnet masking. CIDR notation is a compact representation of an IP address and its associated routing prefix.

Give Subnet (CIDR)

Include IP Address

Exclude IP Address

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Instead of directly asking for donations, I'm thrilled to offer you all nine of my books for just $9 on leanpub By grabbing this bundle you not only help cover my coffee, beer, and Amazon bills but also play a crucial role in advancing and refining this project. Your contribution is indispensable, and I'm genuinely grateful for your involvement in this journey!

Any private key value that you enter or we generate is not stored on this site, this tool is provided via an HTTPS URL to ensure that private keys cannot be stolen, for extra security run this software on your network, no cloud dependency

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A broadcast address is a logical address at which all devices connected to a multiple-access communications network are enabled to receive datagrams.
A message sent to a broadcast address is typically received by all network-attached hosts, rather than by a specific host

For example A /24 network may be divided into the following subnets by increasing the subnet mask successively by one bit. This affects the total number of hosts that can be addressed in the /24 network

Prefix size	Subnet mask	Available subnets	Usable hosts per subnet	Total usable hosts
/24	255.255.255.0	1	254	254
/25	255.255.255.128	2	126	252
/26	255.255.255.192	4	62	248
/27	255.255.255.224	8	30	240
/28	255.255.255.240	16	14	224
/29	255.255.255.248	32	6	192
/30	255.255.255.252	64	2	128
/31	255.255.255.254	128	2 *

 

The following special addresses and networks exist in IPv4:

0.0.0.0	the "ANY" address that is used by programs to speak to all network interfaces, it is never used directly. The whole network 0.*.*.* is reserved for special purposes (like DHCP).
10.*.*.* 172.16.*.* - 172.31.*.* 192.168.*.*	RFC Definend private address
127.0.0.1	is the localhost address The entire 127.*.*.* network is reserved for (host-)local networking.
169.254.*.*	Link-Local addresses. These are automatically generated by some operating systems and (e.g. MacOS and Linux with Avahi installed) and are only usable for local communication in the LAN segment.
198.18.*.* - 198.19.*.*	Network benchmark tests, this should never be used in production networks.
198.51.100.* 203.0.113.*	TEST-NET-2, Documentation and examples TEST-NET-3, Documentation and examples
224.*.*.*	Multicasts (former Class D network) - e.g. there is no default gateway or broadcast for multicasting
240.0.0.0/4	Reserved (former Class E network)
255.255.255.255	Link Broadcast - this is sent to all hosts on the same network link, but does not cross routers