IP subnet calculator (CIDR)
Calculate the mask, network address, broadcast, usable IP range and number of hosts of an IPv4 network in CIDR notation, like 192.168.1.0/24.
IPv4 subnet calculator
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IP subnet calculator (CIDR): what it is for
Type an IP with the prefix, like 192.168.1.10/24, or with the mask, like 10.0.0.1/255.0.0.0. The calculator shows the mask, wildcard, network address, broadcast, first and last usable IP, total hosts, the binary representation and whether the address is private, public or CGNAT. Enter a longer prefix to split the network into subnets.
Nothing is sent to any server: the conversion happens in your browser.
How to use
- Type the IP with /prefix or mask.
- See the network, broadcast and hosts.
- Split into subnets if you want.
When to use it
- Plan the office network.
- Configure VPCs in the cloud.
- Study for networking certifications.
Frequently asked questions
What does /24 mean?
It is the number of bits in the network mask. A /24 equals the mask 255.255.255.0: the first 24 bits identify the network and the remaining 8 the devices, giving 256 addresses, 254 usable.
Why subtract 2 addresses?
The first address identifies the network itself and the last is the broadcast, which talks to everyone at once. Neither goes to a device. This rule doesn't apply to /31 and /32 networks.
Can I split the network into parts?
Yes. In Split into subnets, choose a longer prefix (for example, /26 inside a /24) and see the resulting subnets.
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.