Is my IP data sent to a server?

No. All IP calculations run 100% in your browser. Your IP addresses and subnet configurations never leave your device.

What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation expresses an IP address and its subnet mask as a single string: IP/prefix-length. For example, 192.168.1.0/24 means the first 24 bits are the network address, leaving 8 bits for host addresses (256 addresses, 254 usable).

What is the difference between a subnet mask and a prefix length?

They represent the same thing in different formats. A prefix length of /24 is equivalent to a subnet mask of 255.255.255.0. The prefix length counts the number of consecutive 1-bits in the mask. CIDR notation (/24) is more compact and modern; subnet masks (255.255.255.0) are the legacy format.

What is the difference between IPv4 and IPv6?

IPv4 uses 32-bit addresses (4 billion possible addresses, nearly exhausted). IPv6 uses 128-bit addresses (340 undecillion addresses). IPv6 addresses are written in hexadecimal groups separated by colons: 2001:db8::1. IPv6 also has built-in features for auto-configuration and security.

What are private IP address ranges?

10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 are reserved for private networks (RFC 1918). These addresses are not routable on the public internet. 127.0.0.0/8 is the loopback range (localhost). 169.254.0.0/16 is link-local (APIPA).

IP Address Tools

Validate, calculate, aggregate, convert and anonymize IPv4 & IPv6 addresses. All processing is 100% client-side.

IPv4 Address

Conversions

Decimal

3232235777

Hex

0xC0A80101

Binary

11000000.10101000.00000001.00000001

IPv6 Mapped

::ffff:c0a8:101

Classification

Private (Class C)

🔒 Not routable on the public internet (RFC 1918)

Privacy / GDPR

Anonymized (/24)

192.168.1.0

Private IP Ranges (RFC 1918)

10.0.0.0/8

Class A — 16,777,214 hosts

172.16.0.0/12

Class B — 1,048,574 hosts

192.168.0.0/16

Class C — 65,534 hosts

About the IP Address Tools

IP address calculations — subnet masks, CIDR ranges, broadcast addresses, usable host counts — are essential for network configuration, cloud infrastructure, and security rules. Doing them mentally is error-prone. This tool calculates subnet details from CIDR notation, validates IPv4 and IPv6 addresses, converts between formats, and aggregates CIDR ranges.

What this tool calculates

Subnet Calculator

From a CIDR block: network address, broadcast address, first/last usable host, subnet mask, wildcard mask, and total host count.

IPv6 Support

Expand compressed IPv6 addresses, compress full addresses, calculate IPv6 subnet details, and convert between IPv4 and IPv4-mapped IPv6.

CIDR Aggregation

Aggregate multiple CIDR blocks into the smallest set of covering prefixes — useful for firewall rules and routing table optimization.

Range to CIDR

Convert an IP address range (start–end) to the equivalent set of CIDR blocks — useful when working with legacy firewall rules.

Frequently asked

Is my IP data sent to a server?: No. All IP calculations run 100% in your browser. Your IP addresses and subnet configurations never leave your device.
What is CIDR notation?: CIDR (Classless Inter-Domain Routing) notation expresses an IP address and its subnet mask as a single string: IP/prefix-length. For example, 192.168.1.0/24 means the first 24 bits are the network address, leaving 8 bits for host addresses (256 addresses, 254 usable).
What is the difference between a subnet mask and a prefix length?: They represent the same thing in different formats. A prefix length of /24 is equivalent to a subnet mask of 255.255.255.0. The prefix length counts the number of consecutive 1-bits in the mask. CIDR notation (/24) is more compact and modern; subnet masks (255.255.255.0) are the legacy format.
What is the difference between IPv4 and IPv6?: IPv4 uses 32-bit addresses (4 billion possible addresses, nearly exhausted). IPv6 uses 128-bit addresses (340 undecillion addresses). IPv6 addresses are written in hexadecimal groups separated by colons: 2001:db8::1. IPv6 also has built-in features for auto-configuration and security.
What are private IP address ranges?: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 are reserved for private networks (RFC 1918). These addresses are not routable on the public internet. 127.0.0.0/8 is the loopback range (localhost). 169.254.0.0/16 is link-local (APIPA).