Aaron Graves, PhDude (Replica)

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ip address ranges calculator

Posted on February 16, 2026 by Admin

IPv4 Address Range Calculator

Enter an IPv4 address and CIDR prefix to instantly calculate network boundaries, usable host range, subnet mask, wildcard mask, and address counts.

Enter values and click Calculate Range.

What is an IP address range calculator?

An IP address range calculator is a networking tool that converts an IPv4 address plus a subnet size (CIDR prefix) into practical information: the network address, broadcast address, first usable host, last usable host, and total host capacity. Instead of doing binary math by hand, you can quickly get accurate subnet boundaries in seconds.

Whether you're configuring a home router, designing cloud VPC subnets, writing firewall rules, or troubleshooting DHCP scopes, this type of calculator helps prevent overlapping ranges, wasted address space, and hard-to-track routing issues.

Why subnet range calculations matter

  • Routing clarity: Routers make forwarding decisions based on network ranges, not single host addresses.
  • Security: Correct ranges are essential when creating ACLs, security groups, and segmentation policies.
  • Capacity planning: Knowing usable host counts avoids subnet exhaustion.
  • Troubleshooting speed: You can quickly validate whether two hosts are in the same subnet.
  • Consistency: Standardized subnet design reduces configuration mistakes across environments.

Quick CIDR refresher

CIDR notation uses a suffix like /24 to indicate how many bits belong to the network portion of an IPv4 address. IPv4 addresses are 32 bits total, so:

  • /24 means 24 network bits and 8 host bits (256 total addresses).
  • /27 means 27 network bits and 5 host bits (32 total addresses).
  • /30 means 30 network bits and 2 host bits (4 total addresses).
  • /32 represents one specific address.
Tip: Subnet mask and CIDR are two ways of expressing the same thing. Example: /24 is 255.255.255.0.

How to use this calculator

Step 1: Enter an IPv4 address

Use dotted-decimal format (e.g., 10.0.12.77 or 172.16.5.14). Each octet must be between 0 and 255.

Step 2: Enter the CIDR prefix

Enter an integer from 0 to 32. Most LAN networks use values between /24 and /27, while point-to-point links often use /31.

Step 3: Click “Calculate Range”

The results include:

  • Network address: Start of the subnet block.
  • Broadcast address: End of the subnet block (not used for host assignment in traditional subnets).
  • First/last host: Typical assignable host range.
  • Total addresses: Full count including network and broadcast where applicable.
  • Usable hosts: Host addresses typically assignable to endpoints.
  • Subnet mask and wildcard mask: Useful for routers, ACLs, and legacy tools.

Common subnet sizes at a glance

  • /24 → 256 total, 254 usable (classic small-to-medium LAN).
  • /25 → 128 total, 126 usable (splits a /24 into two equal subnets).
  • /26 → 64 total, 62 usable.
  • /27 → 32 total, 30 usable.
  • /28 → 16 total, 14 usable.
  • /29 → 8 total, 6 usable.
  • /30 → 4 total, 2 usable (legacy point-to-point style).
  • /31 → 2 total, typically both usable for point-to-point (RFC 3021).
  • /32 → 1 total, a single host route.

Practical examples

Example 1: 192.168.10.73/24

Network: 192.168.10.0, Broadcast: 192.168.10.255, Usable hosts: 192.168.10.1 to 192.168.10.254. Great for office or home networks.

Example 2: 10.15.8.201/27

A /27 subnet is broken into blocks of 32 addresses. The calculator places this host in the correct 32-address segment, then shows the exact first and last usable addresses for server assignment and ACL design.

Example 3: 172.20.4.10/31

A /31 has exactly two addresses and is commonly used for router-to-router links. Traditional network/broadcast reservations are not used the same way here.

Frequent mistakes to avoid

  • Confusing network address with a usable host address.
  • Assigning the broadcast address to a device in traditional subnets.
  • Using overlapping subnet ranges in different VLANs or cloud subnets.
  • Mixing up /24 and /16 in firewall rules (this can open far more access than intended).
  • Forgetting that private ranges still need proper internal route design.

Final thoughts

IP planning gets easier when subnet boundaries are visible and precise. Use this calculator anytime you need quick, reliable IPv4 range details for design, deployment, or troubleshooting. If you regularly work with infrastructure-as-code, cloud networking, or enterprise segmentation, keeping a subnet calculator handy will save time and reduce human error.

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