Subnet calculator: address range, mask and network size
IPv4 and IPv6 supported
Examples
Private and carrier rangesWhich networks are private, and which is reserved for ISPs and clouds⌄
- 10.0.0.0/8
- Private network (RFC 1918). The largest local range — 16.7 million addresses, the usual choice for corporate networks and cloud VPCs.
- 172.16.0.0/12
- Private network (RFC 1918). Spans 172.16.0.0 – 172.31.255.255; a common mistake is treating all of 172.x as private.
- 192.168.0.0/16
- Private network (RFC 1918). Home routers almost always hand out addresses from here.
- 100.64.0.0/10
- CGNAT (RFC 6598) — reserved for ISPs running Carrier-Grade NAT: the subscriber gets an address from here and leaves through a shared public IP. Clouds use the same range for internal addressing (AWS EKS pods, for example), so avoid it inside a VPC.