🌐 IP Address/Subnet Calculator

Immediately calculates network addresses, subnet masks, host ranges, etc. from IP addresses and CIDR prefixes.

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subnet partitioning

List of subnets when dividing the current network into smaller subnets.

Calculate an IP address in the form above to see the subnet breakdown.

same-subnet determination

Check if two IP addresses belong to the same subnet.

Usage and Application Examples

  • Check subnet ranges and number of hosts during network design
  • Verify network settings on servers and routers
  • Utilize CIDR block planning in VPC and cloud environments
  • Calculate network addresses required for firewall rules

What is IP Subnet Calculator?

A subnet calculator instantly computes network addresses, broadcast addresses, and usable host ranges from an IP address and subnet mask (CIDR notation). It solves a fundamental networking problem: given an IP and mask, what addresses can you assign to devices, and which are reserved for network/broadcast? Understanding subnetting is crucial for network design—proper subnetting prevents IP conflicts, improves security through segmentation, and optimizes address allocation. This tool eliminates manual binary calculations that are error-prone and tedious.

How to Use

• Enter an IP address (e.g., 192.168.1.0) and subnet mask (e.g., /24 or 255.255.255.0)
• Click Calculate to generate the subnet breakdown
• The tool displays: network address, broadcast address, first usable IP, last usable IP, total hosts
• Review the binary representation to understand how the mask splits network and host portions
• Copy results into your network documentation or device configuration

The calculator supports both CIDR notation (/24) and dotted decimal masks (255.255.255.0). It handles IPv4 and IPv6 inputs, making it versatile for modern mixed-protocol networks.

Use Cases

• Designing a corporate network: You have a /16 block and need to divide it into department subnets. Calculate /24 subnets for Sales, Engineering, and HR to determine how many IPs each gets.
• Setting up VLANs: Your switch needs separate subnets for guests, staff, and IoT devices. Use the calculator to design non-overlapping ranges that won't cause routing conflicts.
• Configuring a VPN: Your remote office needs a /25 subnet that doesn't overlap with HQ. Verify the exact host range before assigning it in your VPN gateway.
• Troubleshooting connectivity: Two devices claim to be on the same subnet but can't ping each other. Calculate the actual subnet to verify they're truly in the same range.

Tips & Insights

Subnetting is rooted in binary math: the subnet mask determines how many bits represent the network versus hosts. A /24 mask uses 24 network bits and 8 host bits, allowing 256 addresses (254 usable after subtracting network and broadcast). Common mistakes: forgetting the network and broadcast addresses are not assignable, or miscalculating with non-standard masks like /25 or /30. This calculator removes guesswork. Understanding subnetting is essential for any networking role and improves security by enabling proper network segmentation and access control.

Frequently Asked Questions

What is a subnet mask?

The subnet mask is a 32-bit value that distinguishes the network and host portions of an IP address. For example, in the case of 255.255.255.0 (/24), the upper 24 bits are the network portion and the lower 8 bits are the host portion.

What is CIDR?

CIDR (Classless Inter-Domain Routing) is a method of IP address assignment and routing. It describes the number of bits in the network section after a slash, such as "/24." It allows more flexible network partitioning than conventional class-based addressing.

What is a private IP address?

An IP address range defined in RFC 1918 that is not routed over the Internet: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. It is widely used in home and corporate internal networks.

How many hosts are available in the /24 network?

The /24 network allows for 254 hosts; there are 256 addresses in the 8-bit host section, excluding the two network addresses (.0) and the broadcast address (.255).

What is a broadcast address?

A broadcast address is a special address for sending data simultaneously to all hosts in that network. It is an address with all the bits in the host part set to 1. For example, the broadcast address for 192.168.1.0/24 is 192.168.1.255.

Is the data entered secure?

Yes. All calculations are completed within your browser, and no IP address or network information you enter is ever sent to our servers. You can use our service with peace of mind.

What is the difference between network address and broadcast address?

The network address is the first address in a subnet and identifies the entire network. The broadcast address is the last address and is used to send messages to all devices in that subnet simultaneously.

How do I calculate subnets for a large network?

Enter your network's IP address and subnet mask (or CIDR notation) into the calculator. The tool will immediately show all subnets, available hosts, and ranges, eliminating manual calculations and reducing errors.

What are Class A, B, and C IP addresses?

These are legacy IP address classifications: Class A (1-126) supports large networks, Class B (128-191) supports medium networks, and Class C (192-223) supports small networks. Modern networks use CIDR notation instead, which is more flexible and efficient.

How many subnets can I create from a larger network?

The number of subnets depends on how many host bits you convert to network bits. For example, a /22 network can be subdivided into four /24 subnets. This calculator helps you plan subnet divisions for optimal network organization.

What is the purpose of subnet masks?

Subnet masks separate the network portion of an IP address from the host portion, allowing routers to determine if an address is on the same local network. They enable efficient network segmentation and control of how many devices can exist on each subnet.

How do I find the host range in a subnet?

The host range is between the network address (first) and broadcast address (last). This calculator automatically displays the usable host range, excluding the network and broadcast addresses which cannot be assigned to devices.