What does this tool do?
The CIDR Calculator takes a CIDR notation such as 192.168.1.0/24 and instantly computes the network address, broadcast address, usable IP range, subnet mask, wildcard mask, IP class, and host count. It saves time for network admins, system engineers, and students learning subnetting.
How to use it
- Enter an address, domain or value.
- View the results instantly.
- Copy the details you need.
What the results mean
The network address is the first address in the subnet; the broadcast address is the last and is used to reach every device at once. The first and last usable IPs give the range you can assign to devices. A /24 has 256 total addresses but 254 usable hosts because the network and broadcast addresses are reserved. The subnet mask (255.255.255.0) and wildcard mask (0.0.0.255) are complements of each other, with the latter common in firewall and ACL rules.
Prefix length and edge cases
The prefix ranges from /0 to /32. A smaller prefix means a larger network: /16 holds 65,536 addresses while /24 holds 256. A /31 is designed for point-to-point links where both addresses are usable, and a /32 points to a single host. The IP class row shows A, B, C, D (multicast), or E (reserved) based on the first octet, which helps you understand the classic address blocks behind modern CIDR.
Frequently asked questions
Why does a /24 network have 254 hosts and not 256?
Of the 256 total addresses, the network address and broadcast address cannot be assigned to devices, leaving 254 usable hosts. The /31 and /32 prefixes are exceptions to this.
What is a wildcard mask used for?
The wildcard mask is the bitwise inverse of the subnet mask (e.g. 0.0.0.255 for 255.255.255.0). It is used to match address ranges in configurations such as Cisco ACLs and OSPF.
What if the IP I enter is not the network address?
That is fine. The tool aligns the IP with the mask to compute the correct network address and range automatically, and it returns a normalized CIDR notation.
Is CIDR Calculator free?
Yes. CIDR Calculator and all 300+ tools on MagmaNex are completely free with no signup or account required.
Is my data safe?
Yes. Everything runs locally in your browser. The data you enter is never sent to a server, stored, or shared.
Does it work on mobile?
Yes. CIDR Calculator works on phones, tablets and desktops — no app download needed.
🔒 Privacy: everything runs in your browser, your data is never sent to a server.