Subnet Calculator
CIDR in — network, broadcast, host range, and mask out. IPv4 math in your browser.
IPv4 subnet
CIDR in → network, broadcast, usable hosts, mask. Private in your browser.
Presets
Also accepts IP mask like 10.0.0.5 255.255.255.0
Results
Network
192.168.1.0/24
Broadcast
192.168.1.255
CIDR
192.168.1.10/24
Netmask
255.255.255.0
Wildcard
0.0.0.255
Usable host range
192.168.1.1 – 192.168.1.254
Total addresses
256
Usable hosts
254
Class
C
Scope
Private (RFC 1918 · 192.168.0.0/16)
How to use this subnet calculator
- Enter a CIDR like
192.168.1.10/24, or an IP plus dotted mask. - Or edit IP, prefix (/0–/32), and subnet mask — they stay linked.
- Read network, broadcast, usable range, wildcard, class, and private vs public scope.
- Copy any row or the full summary for tickets and runbooks.
CIDR math without the spreadsheet
VPC CIDRs, Docker bridges, home LANs, and firewall rules all land on the same questions: what is the network address, what is broadcast, how many hosts fit, and what is the wildcard for an ACL. This page answers those for IPv4 — including /31 point-to-point (RFC 3021) and /32 host routes — without uploading anything.
Need binary or hex for the same numbers? Use the Number Base Converter. For checksums of configs or scripts, try the Hash Generator.
Frequently asked questions
What is CIDR notation?
CIDR writes an IP and a prefix length together, like 192.168.1.0/24. The /24 means the first 24 bits are the network; the rest are hosts.
How many usable hosts does a /24 have?
256 addresses total; typically 254 usable (first is network, last is broadcast). /31 and /32 are special cases — see the notes in the results.
What is a wildcard mask?
The bitwise inverse of the subnet mask (e.g. 0.0.0.255 for /24). Used in ACLs on many routers and firewalls.
Does this support IPv6?
No. This tool is IPv4 only. IPv6 prefix math is a different workflow.
Is my network data uploaded?
No. All CIDR and mask math runs in your browser.