Type a range
Enter CIDR notation (192.168.1.0/24), a bare IP, or an IPv4 netmask (10.0.0.0/255.0.0.0). IPv6 works too — results appear as you type.
Free tools · Network
Subnet math, answered instantly.
Ranges, usable hosts, membership checks and subnet splitting for IPv4 and IPv6 — computed on your device, never uploaded.
Subnet math
Type a range, get the answers.
Accepts 192.168.1.0/24, a bare IP, host bits set, or an IPv4 netmask (10.0.0.0/255.0.0.0). IPv6 works too. Everything computes on your device.
- 192.168.1.0/26192.168.1.0 – 192.168.1.63
- 192.168.1.64/26192.168.1.64 – 192.168.1.127
- 192.168.1.128/26192.168.1.128 – 192.168.1.191
- 192.168.1.192/26192.168.1.192 – 192.168.1.255
How it works
Three steps, all on your device.
The same arithmetic lives in every network planner and IPAM tool, running here without accounts or uploads.
Read the block
Network, broadcast, netmask, usable range, host counts and address type, plus a one-click summary for tickets and docs.
Check and split
Test whether an address sits inside the range, or split the block into longer-prefix subnets with per-row copy buttons.
Questions
Calculating CIDR ranges, answered.
If you manage servers by hand, see the engineering services behind this tools series.
Is my input uploaded anywhere?
No. Subnet math runs entirely in your browser — the page makes no network requests at all. You can verify this in your browser's developer tools or disconnect from the network after the page loads.
How many usable hosts does my subnet have?
For IPv4, subtract the network and broadcast addresses: a /24 holds 256 addresses with 254 usable. Two exceptions: /31 links (RFC 3021) put both addresses to work with no broadcast, and /32 is a single host. IPv6 has no broadcast, so the whole range is addressable.
What does it mean when host bits are set?
An address like 192.168.1.77/24 names a host inside the 192.168.1.0/24 block rather than the block itself. The tool accepts it and computes from the network address, flagging what happened so there is no silent surprise.
Which IPv6 forms are accepted?
Full, compressed (::), and embedded-IPv4 forms such as ::ffff:192.0.2.1. Output follows RFC 5952: lowercase, shortest :: placement for the longest zero run. Zone IDs (fe80::1%eth0) are rejected — strip the zone first.
Why is splitting capped at 4096 subnets?
Rendering tens of thousands of rows would freeze the page without helping anyone plan. If you need more than 4096 subnets, split in two stages: take a longer prefix first, then split one of its children.
How do I use the results on a server or router?
Copy the network/prefix for interface configs and firewall rules, the usable range for DHCP pools and static assignments, and the summary block straight into change tickets. Reserve the network and broadcast addresses — assign only from the usable range.