Networking Calculators

CIDR Notation Explained: What /24, /26, and Other Prefixes Mean

The number after the slash in CIDR notation (like the 24 in 192.168.1.0/24) is a bit count, not a percentage or a version number — it tells you how many of the address's 32 bits are fixed as the network portion, and every single bit of difference doubles or halves the number of addresses in the block.

How IPv4 Subnetting Is Calculated

An IPv4 subnet's network address, broadcast address, and usable host range all come from applying the CIDR prefix as a bitmask to the IP address — with a special two-address exception for point-to-point /31 links.

How IPv6 Subnetting Is Calculated

IPv6 subnetting works the same way as IPv4 — masking the address by a prefix length — but with 128-bit addresses instead of 32-bit ones, producing address counts so large they're shown as exact text rather than a rounded number.

How to Calculate a Subnet Mask, Network Address, and Usable Host Range

Given an IPv4 address and a CIDR prefix (like /26), the subnet mask, network address, broadcast address, and usable host range are all derived through bitwise AND/OR/NOT operations on the address and mask — not separate lookups, but four related outputs of the same underlying arithmetic.

What Are Broadcast and Wildcard Addresses? (And How They Differ from the Subnet Mask)

The broadcast address is a real, reserved IP address used to reach every host in a subnet at once; the wildcard mask is not an address at all but the bitwise inverse of the subnet mask, used in access-control-list and routing configuration syntax — the two are easy to confuse because they're derived from the same subnet mask, but they serve completely different purposes.