IPv4 Subnet Calculator
Enter an IPv4 address and CIDR prefix to view complete subnet details
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Subnet inputs
Enter an IPv4 address and CIDR prefix length
IP addresses are calculated locally in your browser and are never uploaded
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Result
Results update as you type
- Network address
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- Broadcast address
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- Usable host range
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- Total addresses
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- Usable hosts
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- Wildcard mask
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Tool guide
Enter any valid IPv4 address and a CIDR prefix from 0 to 32. The tool calculates the network address, mask, broadcast address, and host range for that subnet entirely in your browser.
- Supports every IPv4 CIDR prefix from /0 to /32
- Handles /31 point-to-point networks and /32 single-host addresses
- Privacy: IP addresses are calculated locally in your browser and are never uploaded
Standards references
The prefix-length and address-block model follows IETF RFC 4632 (CIDR). The special use of two-address /31 networks on point-to-point links is defined by IETF RFC 3021. This calculator reports address arithmetic only; it does not test routing, allocation ownership, firewall rules, or reachability.
FAQ
What is a CIDR prefix length?
In CIDR, /24 means the first 24 bits of the subnet mask are network bits, equivalent to 255.255.255.0. A larger prefix leaves fewer addresses in the subnet.
Why do /31 and /32 not have a normal usable host range?
A /32 represents one address. A /31 is commonly used for point-to-point links, where both addresses can be endpoints, so the tool shows results for that use.