IP & CIDR Calculator

Find exact IPv4 and IPv6 network boundaries, ranges, masks, and address counts.

Exact local calculations · no lookups or network requests

Address and prefix

Enter one address in CIDR notation. Prefixes can be /0–/32 for IPv4 or /0–/128 for IPv6.

Detected IPv4 with a /27 prefix.

Range data is not a security verdict. A valid result does not mean an address is assigned, reachable, public, trusted, or safe.

Subnet results

IPv4

192.0.2.64/27

Total addresses

Usable hosts

Normalized input: 192.0.2.73/27
Network CIDR: 192.0.2.64/27
Network address: 192.0.2.64
First addressInclusive range start: 192.0.2.64
Last addressInclusive range end: 192.0.2.95
Address rangeInclusive: 192.0.2.64 – 192.0.2.95
Total addressesExact count: 32
Netmask: 255.255.255.224
Wildcard mask: 0.0.0.31
Broadcast address: 192.0.2.95
First usable host: 192.0.2.65
Last usable host: 192.0.2.94
Usable host range: 192.0.2.65 – 192.0.2.94
Usable hostsExcludes network and broadcast: 30

Complete tool guide

IP & CIDR Calculator guide

Calculate exact IPv4 and IPv6 network boundaries from CIDR notation, with canonical address formatting and no DNS or network lookup.

All address parsing and range math runs locally in the current browser tab. IPv6 calculations use exact 128-bit integer arithmetic.

Why use this tool?

See the network, inclusive address range, and exact address count at a glance.
Get IPv4 netmask, wildcard mask, broadcast, and conventional usable-host details.
Normalize expanded or compressed IPv6 input into a consistent compressed form.

Common use cases

Checking subnet boundaries while reviewing a firewall or allowlist change
Planning IPv4 address allocation and point-to-point links
Verifying IPv6 prefixes in infrastructure or incident-response notes

How to use it

1
Enter one IPv4 or IPv6 address followed by a slash prefix.
2
Check the detected address family and normalized network CIDR.
3
Review the inclusive range and family-specific details.
4
Copy the plain-text summary into your change record or investigation notes.

CIDR boundaries

Host bits are cleared to find the network and set to one to find the final address. Counts and endpoints are inclusive.

IPv4 host conventions

For /0 through /30, the network and broadcast addresses are excluded from usable hosts. A /31 exposes both addresses for point-to-point use, and a /32 represents one host.

IPv6 formatting

IPv6 output is lowercase, removes leading zeroes, and compresses the longest run of zero hextets. IPv6 has no broadcast address.

Practical tips for better results

Use documentation prefixes in examples: 192.0.2.0/24, 198.51.100.0/24, and 2001:db8::/32.
A mathematically valid range does not prove that an address is assigned, reachable, trusted, or safe.
Confirm provider- and platform-specific reservations before deploying a subnet plan.

Frequently asked questions

Does this tool contact the address or perform DNS lookups?

No. It only parses the text and performs local integer calculations in this browser tab.

Why are both addresses usable in an IPv4 /31?

The calculator follows the conventional RFC 3021 point-to-point interpretation, which does not reserve separate network and broadcast hosts in a /31.

Does IPv6 have a broadcast address?

No. The final IPv6 address shown is simply the inclusive end of the prefix range, not a broadcast address.

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