Subnet Calculator

Written byOleh Soloninupdated 25 September 2026

IP Address

CIDR

Result

Network192.168.1.0
Broadcast192.168.1.255
Host Range192.168.1.1 - 192.168.1.254
Usable Hosts254

What a /24 actually contains

Enter an IPv4 address and prefix to get the network address, broadcast address, usable host range and host count.

Subnetting is the piece of networking most people re-learn every time they need it. The prefix says how many bits identify the network, and everything left over addresses hosts.

A /24 leaves eight host bits, which is 256 addresses — but two are reserved, one for the network itself and one for broadcast, leaving 254 you can assign.

How to use

Enter any address in the network — the calculator works out the network address itself.
Set the prefix length: it says how many bits belong to the network and how many to hosts.
Read off the usable range: the first and last addresses of a network are taken.

Why the address count jumps

Every bit that moves from the network to the host part doubles the number of addresses. There are no in-between sizes: nothing sits between a /25 with 126 usable addresses and a /24 with 254. Two hundred devices need a /24.

Two addresses come off every network: the first names the network itself, the last is the broadcast address. The exceptions are /31 and /32, which have neither.

Every row comes from the calculator on this page. Until recently it reported "no usable hosts" for both /31 and /32; under RFC 3021 both addresses of a /31 are usable — that is how the two ends of a single link are numbered — and a /32 means exactly one machine.
Prefix	Addresses	Usable	Example for 192.168.1.10
/24	256	254	192.168.1.1 – 192.168.1.254
/26	64	62	192.168.1.1 – 192.168.1.62
/30	4	2	192.168.1.9 – 192.168.1.10
/31	2	2 — per RFC 3021	192.168.1.10 – 192.168.1.11
/32	1	1 — a single host	192.168.1.10

What this calculator shows

Network and broadcast addresses for your subnet
The first and last usable host address
How many hosts the prefix actually allows

What to keep in mind

IPv4 only, in dotted-decimal notation.
Network and broadcast addresses are excluded from the usable count, per standard practice.

FAQs

How many hosts fit in a /24?

254. There are 256 addresses in total, minus the network address and the broadcast address.

What does the /24 mean?

The first 24 bits identify the network, equivalent to a 255.255.255.0 mask. The remaining 8 bits address individual hosts.

How many usable addresses do /31 and /32 have?

Two for a /31, one for a /32. RFC 3021 allows /31 on point-to-point links: there is no network or broadcast address, and both addresses go to the two ends of the link. A /32 names a single machine — how a route to one host or a loopback address is written.

Why use a /31 when a /30 exists?

To stop wasting addresses. A /30 has four addresses of which only two work; a /31 gives the same two with nothing lost. On a network with hundreds of router links that halves the addresses consumed.

What makes an address private?

Three ranges are reserved for internal use: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. They are not routable on the public internet, which is why the same ranges exist in every home and office at once.

What does a 169.254.x.x address mean?

That the device gave itself a link-local address, as RFC 3927 allows. On a network where a router should hand out addresses by DHCP, it usually points to DHCP trouble — check the DHCP server and the link — though the address alone does not prove the connection works or that no lease was ever received.

Worked example

A typical office network

Input: 192.168.1.50/24

Output: Network 192.168.1.0 · Broadcast 192.168.1.255 · Hosts .1 to .254

Note: 254 usable addresses, not 256. Forgetting the two reserved ones is the classic off-by-two in capacity planning.

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