IP Subnet CalculatorFree online other calculator — instant results, no sign-up

Subnet Mask = (~0 << (32 − c)) >>> 0
Network Address = (IP AND Subnet Mask) >>> 0
Broadcast Address = (Network Address OR NOT Subnet Mask) >>> 0
Usable Hosts = max(0, 2^(32 − c) − 2)
Usable Host Range = (Network Address + 1) to (Broadcast Address − 1)

• cCIDR prefix length (number of network bits)
• IP32-bit integer representation of the input IPv4 address
• Subnet Mask32-bit integer with c leading 1-bits and 32 − c trailing 0-bits
• Network AddressLowest numeric address in the block, reserved to identify the network
• Broadcast AddressHighest numeric address in the block, reserved for broadcast traffic to all hosts

The calculator parses the dotted-decimal IP address into a 32-bit unsigned integer and converts the prefix length into a 32-bit subnet mask bitmask. It uses bitwise AND to isolate the network address and bitwise OR with the inverted mask to calculate the broadcast address. The usable host count is calculated using the formula 2^(32 − c) − 2, floored at 0, and converted back to standard dotted-decimal notation for display.

These are the calculator's starting values and the results it actually produces for them.

1. 1Verify the IP address contains four octets between 0 and 255, then pack them into a 32-bit unsigned integer.
2. 2Derive the 32-bit subnet mask by shifting 32 minus the CIDR prefix length.
3. 3Compute the network address by taking the bitwise AND of the IP and mask, and compute the broadcast address by taking the bitwise OR of the network address and the inverted mask.
4. 4Calculate the usable host capacity and format the network, broadcast, mask, and usable host range (network + 1 through broadcast − 1) into dotted-decimal strings.