CIDR Calculator – IP Range & Subnet Calculator

Quickly convert IP plus CIDR prefix into subnet mask, network address, broadcast, and host count — essential for cloud VPCs and CCNA labs.

A CIDR calculator computes all parameters of a classless IPv4 subnet from an address and prefix length (such as 192.168.1.0/24).

CIDR (Classless Inter-Domain Routing) replaced class A/B/C sizing and is the standard for routing and firewall documentation today.

• Enter an IPv4 address (e.g. 192.168.1.10).
• Enter CIDR as /24 or select prefix from the dropdown.
• Click Calculate.
• Copy network range, mask, and host counts.

Network = IP AND subnet mask. Broadcast = network OR wildcard mask. Usable hosts = 2^(32−prefix) − 2 (except /31 and /32).

Subnet mask from prefix: set the leftmost `prefix` bits to 1 in a 32-bit word.

Sample inputs and expected outputs:

• Network address — first address of the subnet (host bits zero).
• Broadcast — last address on the segment (host bits one).
• Host range — assignable addresses between network and broadcast.
• CIDR notation — compact form for route tables and cloud APIs.

• AWS/Azure subnet design
• ACL documentation
• CCNA subnetting practice
• IPAM audits

• Instant CIDR math
• No binary worksheet
• Consistent with RFC definitions
• Copy-ready results

Avoid these errors when using this network calculator:

• RFC 950 — Internet Standard Subnetting
• RFC 1519 — Classless Inter-Domain Routing (CIDR)
• RFC 4632 — CIDR Address Allocation
• IANA — IPv4 Address Space
• Cisco — IP Addressing and Subnetting

This calculator is for education, lab work, and network planning. Always verify production firewall, routing, and cloud VPC settings before deployment.