Subnet Calculator
Calculate subnet ranges from an IP and CIDR prefix, an IP and subnet mask, or a required host count. This tool shows network boundaries, usable host range, subnet mask details, and related addressing information.
Subnet Results
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What this tool does
Subnet Calculator helps you work out the boundaries of an IPv4 subnet from several starting points. You can enter an IP and CIDR prefix, an IP and dotted-decimal subnet mask, or an IP and required usable host count.
The tool returns the network address, broadcast address, usable host range, total address count, subnet mask, wildcard mask, and a few related networking details.
When this tool is useful
- Planning VLANs and small network segments
- Checking the valid host range for an existing subnet
- Converting subnet masks into CIDR notation
- Sizing a subnet based on required host count
- Working out reverse PTR zones for IPv4 ranges
Learn more
Related Articles
How to calculate a subnet range
A practical guide to calculating network address, broadcast address, and usable host range from an IP address and subnet size.
What is a subnet mask?
Learn what a subnet mask does, how it defines network boundaries, and how it relates to CIDR notation and usable host ranges.
CIDR cheat sheet (common subnet sizes)
Quick reference for common CIDR ranges, subnet masks, block sizes, and usable host counts for fast subnet calculations.