Private IP checker
- Network address
- 100.72.14.9
- Broadcast address
- —
- First usable host
- 100.72.14.9
- Last usable host
- 100.72.14.9
- Usable hosts
- 1
- Total addresses
- 1
- Subnet mask
- 255.255.255.255
- Wildcard mask
- 0.0.0.0
- CIDR notation
- 100.72.14.9/32
- Address range
- 100.72.14.9 – 100.72.14.9
- Class
- A
- Scope
- Carrier-grade NAT (RFC 6598)
- Mask in binary
- 11111111.11111111.11111111.11111111
- Address in binary
- 01100100.01001000.00001110.00001001
A /32 is a single host — a host route, not a network.
- Smallest block for 50 hosts
- /26
Calculated in your browser · nothing is looked up or uploaded
Says whether an IPv4 address is public, private, loopback, link-local, carrier-grade NAT, multicast or reserved, and therefore whether it can be reached from the internet.
How to use the private ip checker
Three blocks are private under RFC 1918: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. The middle one is where mistakes live: it covers 172.16 through 172.31, not all of 172, so 172.15.0.1 and 172.32.0.1 are public addresses that look private at a glance.
Four other ranges answer questions people actually have. 169.254.x.x means DHCP failed and the machine assigned itself a link-local address — that is a fault report rather than a configuration. 100.64.0.0/10 is carrier-grade NAT: your ISP is sharing one real address between many customers, which is why port forwarding on your router does nothing and why a "public IP" you looked up may be unreachable. 127.x.x.x is all loopback, not just 127.0.0.1 — the entire /8 is reserved for it. And 224.0.0.0/4 is multicast, which is not a host address at all.
Worth stating plainly because the confusion is common: an address being private says nothing about whether it is secure. Private addresses are not routable on the internet, which is a routing property, not a security boundary. Anything on the same network reaches them freely.
Questions
10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. The middle one is 172.16 to 172.31 only.
DHCP failed and the machine assigned itself a link-local address. It is a fault, not a setting.
Possibly carrier-grade NAT — a 100.64 to 100.127 address means your ISP shares one real address between customers.
Yes. The whole 127.0.0.0/8 block is loopback, not just 127.0.0.1.
No. It means not routable on the internet, which is a routing property. Anything on the same network reaches it freely.
No. It is arithmetic on the address you type — nothing is queried and nothing leaves your browser, which is why it works on an internal network with no connectivity.