IP Subnet Calculator
Calculate network, broadcast, mask, host range, and total addresses for any IPv4 CIDR. Free online tool, no signup required.
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Frequently asked questions
- What is CIDR notation?
- CIDR (Classless Inter-Domain Routing) writes a network as IP/prefix. /24 means the first 24 bits are the network portion, leaving 8 bits (256 addresses) for hosts.
- Why are usable hosts 2 fewer than total?
- In a /24 (256 total), the network address (.0) and broadcast address (.255) cannot be assigned to hosts, leaving 254 usable. /31 and /32 are special cases used for point-to-point links.
- What is a wildcard mask?
- The bitwise inverse of the netmask. Used in Cisco access control lists (ACLs) where 0 means "must match" and 1 means "any." For /24 the wildcard is 0.0.0.255.
- Does this support IPv6?
- No, this calculator handles IPv4 only. IPv6 uses 128-bit addresses with different conventions and a much larger address space.
- What is the difference between /24 and 255.255.255.0?
- They are the same thing in two notations. The /24 prefix means the first 24 bits are 1s, which is exactly 255.255.255.0 in dotted-decimal form.