/24 subnet: mask 255.255.255.0, 254 usable hosts

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Updated Oct 8, 2026

Examples

IP address / CIDR / netmask

IPv4 or IPv6, with or without a prefix — 10.0.0.0/8, 2001:db8::/48, or a dotted netmask like 192.168.1.0 255.255.255.0. A bare address means one host (/32 or /128).

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fig. 10 — subnet-calculator · networking /24 — 254 usable hosts

Result

IPv410.0.0.0/24

Usable hosts254

Usable range10.0.0.1 – 10.0.0.254

Total addresses256

Addressing

Network address: 10.0.0.0
Broadcast address: 10.0.0.255
Usable host range: 10.0.0.1 – 10.0.0.254

Masks

Netmask: 255.255.255.0
Wildcard maskInverse of the netmask — the match form Cisco ACLs and OSPF expect.: 0.0.0.255
Netmask (binary)The mask bit by bit — the 1s are the network part.: 11111111.11111111.11111111.00000000

Details

Address type: Private (RFC 1918)
Network (integer)The network address as a single 32-bit number, as scripts and databases store it.: 167 772 160

Check against CIDRs Split this subnet Convert this address

A /24 is the netmask 255.255.255.0: 256 addresses, 254 usable hosts, one value of the last octet per address. It is the default size for a LAN, a VLAN or a cloud subnet tier.

What /24 means

Twenty-four network bits cover the first three octets exactly, so the mask is 255.255.255.0 and the wildcard 0.0.0.255. That octet alignment is why /24 is the easiest prefix to reason about: the last number is the host, the first three are the network.

Host math: 2^8 = 256 addresses, minus network and broadcast leaves 254. For 10.0.0.0/24 the usable range is 10.0.0.1 to 10.0.0.254, and 10.0.0.255 is the broadcast.

Where /24 is used

Most home routers, office VLANs and lab networks are /24s. It is also the smallest prefix generally accepted on the public internet: many providers filter IPv4 announcements longer than /24, so a /24 is the minimum block worth announcing over BGP.

In AWS and Azure a /24 subnet keeps 251 assignable addresses after the five reserved ones (network, router, DNS, a spare and broadcast). Google Cloud reserves four, leaving 252.

Splitting and adjacent prefixes

A /24 halves into two /25s of 126 usable hosts, quarters into four /26s, and splits into eight /27s or sixteen /28s. Going up, two aligned /24s form a /23 and four form a /22.

Do not size by the round number. A /24 with a dozen servers wastes nothing locally, but in a shared address plan those 240 idle addresses are gone from every other team.

Configuring and checking a /24

On Linux, ip addr add 10.0.0.10/24 dev eth0 assigns a host address with this mask; Windows and router UIs ask for 255.255.255.0 instead. The gateway is conventionally 10.0.0.1 or 10.0.0.254; pick one convention for the whole estate and keep it.

If two hosts on what should be one /24 cannot reach each other, compare their masks first. A single host configured as /25 or /16 by accident produces asymmetric reachability that is easy to misread as a firewall problem.

FAQ

Questions, answered.

Tap a question to expand the answer.

How many usable IP addresses are in a /24?

254. A /24 has 256 addresses; the first is the network address and the last is the broadcast.

What is the subnet mask for /24?

255.255.255.0, with wildcard mask 0.0.0.255.

How many usable IPs does a /24 have in AWS?

251. AWS reserves five addresses in every subnet.

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