IP CIDR calculator
- Network address
- 172.16.32.0
- Broadcast address
- 172.16.47.255
- First usable host
- 172.16.32.1
- Last usable host
- 172.16.47.254
- Usable hosts
- 4,094
- Total addresses
- 4,096
- Subnet mask
- 255.255.240.0
- Wildcard mask
- 0.0.15.255
- CIDR notation
- 172.16.32.0/20
- Address range
- 172.16.32.0 – 172.16.47.255
- Class
- B
- Scope
- Private (RFC 1918)
- Mask in binary
- 11111111.11111111.11110000.00000000
- Address in binary
- 10101100.00010000.00100000.01100100
- Subnets of /26
- 64
- Usable hosts in each
- 62
- Smallest block for 50 hosts
- /26
Calculated in your browser · nothing is looked up or uploaded
Takes an address with a CIDR prefix and expands it: the network it belongs to, its usable range, its mask, and whether the address is public, private or reserved.
How to use the ip cidr calculator
The question this answers most often is "which network is this address actually in", and the answer surprises people whenever the prefix is not a multiple of eight. 172.16.32.100/20 is in 172.16.32.0/20, which runs to 172.16.47.255 — the third octet boundary lands on 32 and 48 because a /20 leaves four bits of the third octet for hosts.
The scope row is the practically useful one. RFC 1918 reserves 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 for private use, and the 172 range is the one people get wrong: it is 172.16 through 172.31, not all of 172. Two other blocks come up regularly — 169.254.0.0/16 is the link-local range a machine assigns itself when DHCP fails, so seeing one is a diagnosis rather than a configuration, and 100.64.0.0/10 is carrier-grade NAT, which is why a home router can report a "public" address that is not reachable from outside.
Everything is calculated locally, which matters here: this is the tool you want when working on an isolated network with no route to anywhere.
Questions
172.16 through 172.31 only — that is a /12. 172.15 and 172.32 are public.