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Professional IPv4 subnetting tool. Calculate network ranges, broadcast addresses, and usable host counts with bitwise precision.
RFC 1918 Private Ranges
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The IP Subnet Calculator is an essential utility for network architects, system administrators, and cloud engineers. It allows you to visualize IP address distributions, calculate usable host ranges, and plan CIDR-based networks with absolute precision and zero latency.
An IP Subnet Calculator is an essential networking tool used by system administrators, network engineers, and IT students to divide a larger IP network into smaller, more manageable sub-networks (subnets). Our free online CIDR calculator allows you to instantly compute the network address, broadcast address, subnet mask, and the exact range of usable host IP addresses without needing to perform complex binary math manually.
Classless Inter-Domain Routing (CIDR) is the modern standard for defining network boundaries, replacing the old classful network architecture (Class A, B, and C). Instead of typing out complex subnet masks like 255.255.255.0, CIDR uses a simple slash notation followed by the number of 'Network Bits' (e.g., /24). By adjusting the CIDR prefix in our tool, you can instantly see how the network size shrinks or grows. A lower CIDR number (like /8) provides millions of hosts, while a higher number (like /30) provides just two usable hosts, commonly used for point-to-point router connections.
Total IPs - 2.Security is paramount when mapping out corporate networks. Unlike server-side calculators that transmit your configurations over the internet, our Subnet Calculator operates 100% locally in your browser using modern JavaScript APIs. Your IP schemas and private network architecture never leave your device. Zero tracking, zero server logs, and instant calculation speeds—ensuring maximum privacy.
Subnetting is the practice of dividing a single physical network into multiple logical sub-networks. This is critical for improving network performance, increasing security, and managing technical debt in large-scale IP deployments.
By using a subnet mask (such as 255.255.255.0 or /24), you define which part of an IP address refers to the network and which part refers to the individual host device. This tool handles the complex binary math behind these divisions so you can focus on architecture.
CIDR is the modern standard for allocating IP addresses. Instead of relying on rigid 'Class A, B, or C' networks, CIDR allows for variable-length subnet masking. For example, a '/24' network provides 256 addresses, while a '/22' provides 1,024.
Using our calculator, you can instantly see how changing a CIDR suffix impacts your broadcast address, wildcard mask, and the total number of usable host IPs available for your devices.
When planning a new VLAN or cloud VPC, start by identifying the total number of hosts required. Use the calculator to find the smallest CIDR block that fits your needs while allowing for 20% growth.
Our tool provides the dotted-decimal, binary, and hex representations of your network, making it easy to copy-paste configurations directly into Cisco, Juniper, or AWS interfaces.
A subnet mask is a 32-bit number used in IPv4 networking to divide an IP address into two distinct parts: the network address and the host address. It essentially 'masks' the network portion, allowing routers to determine whether a destination IP is strictly on the local network or if it needs to be routed through a gateway to the outside world.
To find the number of usable hosts from a CIDR prefix (like /24), subtract the CIDR number from 32 (the total number of IPv4 bits). E.g., 32 - 24 = 8 bits remaining for hosts. Then, calculate 2 to the power of those remaining bits (2^8 = 256). Finally, subtract 2 (for the network and broadcast addresses). Result: 254 usable hosts.
The Internet Engineering Task Force (IETF) reserved specific IPv4 blocks for private, internal networks. These addresses are not publicly routable on the internet. They are: 10.0.0.0 to 10.255.255.255 (a single Class A network /8), 172.16.0.0 to 172.31.255.255 (16 contiguous Class B networks /12), and 192.168.0.0 to 192.168.255.255 (256 contiguous Class C networks /16).
In any IPv4 subnet, the first address is strictly reserved as the 'Network Identifier' (Network ID), and the final address is strictly reserved as the 'Broadcast Address'. Because core networking protocols require these addresses to function, you can never assign them to an individual host (like a computer or a printer).
No. Our subnet calculator is built with privacy by design. All IPv4 and CIDR calculations are executed entirely on your client-side browser via JavaScript. No data is ever transmitted to, or stored on, any external servers.
A /32 subnet represents a single specific host (1 IP address, 0 usable hosts for a network). A /31 subnet has exactly 2 total addresses, which mathematically leaves 0 usable hosts under normal rules. However, per RFC 3021, a /31 subnet is explicitly used for point-to-point links between two routers, where the network and broadcast addresses are repurposed as the two host IPs.
In every standard subnet, two addresses are reserved: the Network Address (the first one) and the Broadcast Address (the last one). These cannot be assigned to individual devices.
This version is dedicated to IPv4 subnetting. IPv6 support is currently in development and will be released in a future update to the ZeroPingTools suite.
Yes, CIDR notation (like /24) is just a more compact way of writing a subnet mask (like 255.255.255.0). Both tell the network which bits belong to the network prefix.