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Subnet / CIDR Calculator

Calculate IP subnet mask, network address, broadcast address, IP range, wildcard mask, and usable host count from IP and CIDR prefix.

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IP Subnet Mask & Network Range Calculator

Calculate IPv4 network boundaries, wildcard masks, and total usable hosts instantly. Works offline in your browser for DevOps, sysadmins, and network engineers.

How Subnet / CIDR Calculator Works

Paste or enter your input in the field above. Most tools update in real time. Click the Copy button to copy the output. All processing happens in your browser—your data never leaves your device unless the tool explicitly uses a server feature (such as URL shortening or bcrypt hashing).

This tool is part of the Network Tools category. Check similar tools below. All everytools are free, no signup required. Works on desktop and mobile.

Common Use Cases

  • Design VPC and subnet ranges in AWS, Google Cloud, or Azure
  • Calculate usable IP addresses for DHCP pools and router configuration
  • Verify wildcard masks for Cisco ACLs and firewall rules
  • Convert CIDR notation (/27, /28) to dotted decimal subnet masks (255.255.255.224)

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Frequently Asked Questions

What is a CIDR notation?
CIDR (Classless Inter-Domain Routing) notation specifies an IP address and its associated network prefix length (e.g. /24). The prefix number indicates how many leading bits are used for the network ID.
How many usable hosts in a /24 subnet?
A /24 subnet provides 256 total IP addresses, of which 254 are usable for hosts (excluding the network address .0 and broadcast address .255).
What is the difference between Subnet Mask and Wildcard Mask?
A Subnet Mask uses 1s for the network portion (e.g. 255.255.255.0). A Wildcard Mask is the bitwise inverse (e.g. 0.0.0.255), commonly used in Cisco ACLs and OSPF routing.
Is my IP data sent to any server?
No — all subnet calculations are performed entirely in your browser using local JavaScript.