🌐 IP Subnet Calculator

The SolversPro IP Subnet Calculator is a free browser-based networking utility that computes IPv4 network boundaries, broadcast addresses, subnet masks, usable host ranges, and binary representations from any IP address and CIDR prefix in real time.

IP Address

Prefix (CIDR)

Or Enter Subnet Mask

IPv4 Subnet Prefix & Capacity Reference

Standard CIDR prefixes, subnet masks, total address capacity, and usable host counts for network planning.

CIDR Prefix	Subnet Mask	Total IP Addresses	Usable Host Range	Common Use Case
/24	255.255.255.0	256	254	Standard LAN / Office Subnet (Class C)
/25	255.255.255.128	128	126	Department / VLAN Segmentation
/26	255.255.255.192	64	62	Mid-sized Server Subnet
/27	255.255.255.224	32	30	Branch Office / Cloud VPC Subnet
/28	255.255.255.240	16	14	Small DMZ / Appliance Cluster
/29	255.255.255.248	8	6	ISP Static IP Allocation
/30	255.255.255.252	4	2	Point-to-Point Router Link
/32	255.255.255.255	1	1 (Host)	Loopback / Single Host Route

Frequently Asked Questions

What is an IP subnet calculator?

An IP subnet calculator is a networking utility that takes an IPv4 address along with a CIDR prefix (e.g., /24) or dotted-decimal subnet mask (e.g., 255.255.255.0) and calculates the network ID, broadcast address, valid host range, total addresses, and usable host count.

How do you calculate usable host addresses in an IPv4 subnet?

In standard IPv4 subnets (prefixes /1 through /30), usable hosts equal 2^(32 - prefix) - 2. The subtract-2 rule accounts for the network address (all host bits 0) and the broadcast address (all host bits 1), neither of which can be assigned to an individual network interface.

What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation represents an IP address and its associated routing prefix using a slash followed by the count of leading 1-bits in the subnet mask, such as 192.168.1.0/24 instead of 255.255.255.0.

What are /31 and /32 subnets used for?

Under RFC 3021, /31 subnets provide 2 usable addresses exclusively for point-to-point router links without standard broadcast overhead. A /32 prefix denotes a single host route (1 IP address) commonly used for loopback interfaces and firewall host rules.