IP subnet calculator
Inspect an IPv4 or IPv6 CIDR prefix and see its exact network range, masks and address capacity.
Use CIDR for IPv4 or IPv6, for example 192.168.1.10/24 or 2001:db8::1/64.
Checks whether this IPv4 address is a usable gateway in the calculated subnet. It does not select or configure a gateway.
Address arithmetic only—no DNS, ownership, reachability, geolocation or network-policy recommendation.
Included
- Every visible input and selected unit
- Reconciled intermediate values and result breakdown
- Reproducible URL state
Not included
- Address arithmetic only—no DNS, ownership, reachability, geolocation or network-policy recommendation.
What this means
Inspect an IPv4 or IPv6 CIDR prefix and see its exact network range, masks and address capacity.
Address arithmetic only—no DNS, ownership, reachability, geolocation or network-policy recommendation.
Intermediate values are not rounded; only the localized display formats the result.
Formula & worked example
address count = 2^(address bits − prefix length)
192.168.1.10/24
- Inputs
- 32 address bits − 24 prefix bits = 8 host bits
- Calculation
- 2^8 = 256 total addresses; network 192.168.1.0
The range is 192.168.1.0 through 192.168.1.255, with 254 conventionally usable host addresses.
How this calculation works
The calculation follows the formulas, definitions and assumptions explained on this page. The references below support the method and any stated boundaries.
Official sources
- RFC 4632 — Classless Inter-domain Routing — Public definitions and technical semantics used by this calculation
- RFC 3021 — 31-bit IPv4 Point-to-Point Prefixes — Defines the two-address /31 point-to-point convention
- RFC 4291 — IPv6 Addressing Architecture — Defines IPv6 addresses and prefix semantics
- RFC 6164 — 127-bit IPv6 Prefixes on Inter-Router Links — Explains the /127 point-to-point convention