What the Subnet Calculator calculates
An IPv4 address plus a CIDR prefix or contiguous subnet mask identifies one subnet. The calculator normalizes that input into the containing network and shows the address range and mask details.
Files & Data · IPv4 networking
Subnet Calculator
Calculate an IPv4 subnet from an IP address and CIDR prefix or subnet mask. Get the network, broadcast, usable host range, wildcard mask, and address counts.
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Network address—
Broadcast address—
First usable address—
Last usable address—
Usable host range—
Subnet mask—
Wildcard mask—
Prefix length—
Network bits—
Host bits—
Total addresses—
Usable addresses—
RFC 1918 private address—
Show binary breakdown
Network / host boundary: —
The vertical bar in the rows below marks the exact CIDR boundary, including prefixes that split an octet.
IPv4 address
—Subnet mask
—Wildcard mask
—Network
—Final address
—CIDR prefix and subnet mask
A prefix such as /24 means the first 24 bits are network bits. The equivalent subnet mask is 255.255.255.0. You can enter either form.
Network and broadcast addresses
For ordinary IPv4 subnets from /0 through /30, the first address is the network address and the final address is the broadcast address. /31 and /32 are handled separately.
Usable host range
For /0 through /30, the usable range starts one address after the network and ends one address before the broadcast. The app shows both endpoints and the usable-address count.
/31 and /32
A /31 point-to-point subnet uses both addresses as endpoints and does not use the ordinary directed broadcast. A /32 is a single-host route with one address and no broadcast address.
Wildcard mask
The wildcard mask is the 32-bit inverse of the subnet mask. It is commonly used by networking products in address matching and rule syntax.
Worked example
For 192.168.1.130/26, the network is 192.168.1.128, the broadcast is 192.168.1.191, and the usable range is 192.168.1.129–192.168.1.190, giving 62 usable addresses.
IPv4-only scope
This version intentionally calculates IPv4. IPv6 has different addressing semantics, including no broadcast addresses, so it should not reuse IPv4 broadcast and host-range assumptions.