Subnet Calculator
Enter an IP and mask — get network, broadcast, usable range and more.
Subnetting splits networks into smaller pieces — essential for network engineers, homelab builders, and cloud architects. This calculator handles CIDR and dotted masks, validates input, and explains /31 and /32 edge cases.
How to use
- Type an IP with CIDR (192.168.1.0/24) — or an IP plus a mask in the second box.
- Click Calculate to see network, broadcast, usable range, masks and binary.
- Works for every prefix length from /0 to /32, including /31 point-to-point links.
About this tool
All math runs in your browser. No lookups, no tracking.
Frequently asked questions
What is the difference between /24 and 255.255.255.0?
Nothing — they are two notations for the same mask. /24 means the first 24 bits are network bits, which written out is 255.255.255.0.
Why are 2 addresses "unusable"?
In a normal subnet the lowest address is the network identifier and the highest is the broadcast address — neither can be assigned to a host. /31 and /32 are special cases.
Does it support IPv6?
Not yet — this version is IPv4 only.
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