You have a CIDR and need the actual range

Someone hands you 10.0.0.0/22 and asks how many addresses that is, or what the broadcast address is. Doing the bit math in your head is how off-by-one firewall rules get written.

Compute the block

The CIDR / Subnet Calculator takes an IPv4 CIDR and returns the network address, broadcast address, total and usable host counts, and the first and last usable addresses. Paste the block, read the range, and write the rule with confidence.

Context from the host part

When you also need to know what a specific IP in that range resolves to or how it is formed, the URL Parser is not the tool — but knowing the network boundaries first keeps your IP-based logic honest. Start with the subnet, then reason about individual hosts.

Useful for

Writing firewall or security-group rules.
Sizing a VLAN or a private address plan.
Explaining a CIDR to someone who thinks in counts, not masks.

Frequently Asked Questions

Why does a slash twenty four network hold 254 hosts and not 256?

Two addresses in the block are reserved. One names the network itself and one is the broadcast address, so neither can be assigned to a device, leaving two hundred fifty four usable addresses.

How do I know if two ranges overlap?

Compare the first and last address of each block. If either range contains any address from the other, they overlap, and overlapping blocks cause routing confusion that is far easier to prevent before assignment than to debug later.

Does the prefix length have to be a multiple of eight?

No. Any length from zero to thirty two is valid, which is the whole point of classless addressing. A prefix that does not fall on a byte boundary simply splits one octet between the network and the host portion.

Calculate IP ranges from a CIDR block