How many addresses are in a /24?

256 total. Subtracting the network and broadcast addresses leaves 254 usable hosts — this is the most common home-lab and small-office subnet.

Why do two addresses disappear from the usable count?

The lowest address identifies the network itself and the highest is reserved for broadcast, so neither can be assigned to a host. The calculator shows them explicitly so nothing surprises you.

What is a wildcard mask for?

It is the inverted netmask (0.0.0.255 for /24). Access control lists on routers and some firewalls are written with wildcards instead of netmasks, and mixing the two up breaks matching.

How do I calculate a subnet mask from CIDR?

Paste the CIDR (192.168.1.0/24) and the netmask, wildcard, host range and usable count are all derived at once — no manual binary math. /24 → 255.255.255.0, /26 → 255.255.255.192, and so on.

IPv4 Subnet Calculator — Guide

Paste a CIDR like 192.168.1.0/24 and get the full subnet breakdown — usable hosts, first/last address, netmask, wildcard. Built for VPC and VLAN planning, free in your browser.

What it is and when to use it

Paste a CIDR block like 192.168.1.0/24 and get everything a subnet plan needs: network and broadcast addresses, first and last usable host, usable host count, netmask and wildcard mask. Handy for VLAN planning, DHCP scope sizing or double-checking an assignment before you apply it.

Parses a CIDR network and works out the full set of details: usable hosts, first and last address, mask and more.

How to use it

Enter the CIDR (e.g. 192.168.1.0/24)
Read the results below
Copy whichever field you need

A worked example

Fill in a sample network

192.168.1.0/24

Copy this into the tool, or open IPv4 Subnet Calculator

Things that trip people up

The network address and broadcast address normally cannot be assigned to a host

Questions people ask

How many addresses are in a /24?: 256 total. Subtracting the network and broadcast addresses leaves 254 usable hosts — this is the most common home-lab and small-office subnet.
Why do two addresses disappear from the usable count?: The lowest address identifies the network itself and the highest is reserved for broadcast, so neither can be assigned to a host. The calculator shows them explicitly so nothing surprises you.
What is a wildcard mask for?: It is the inverted netmask (0.0.0.255 for /24). Access control lists on routers and some firewalls are written with wildcards instead of netmasks, and mixing the two up breaks matching.
How do I calculate a subnet mask from CIDR?: Paste the CIDR (192.168.1.0/24) and the netmask, wildcard, host range and usable count are all derived at once — no manual binary math. /24 → 255.255.255.0, /26 → 255.255.255.192, and so on.

Next steps

Open the IPv4 Subnet Calculator tool

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