CIDR to IP Range Calculator
This free CIDR calculator converts IPv4 CIDR notation (for example 192.168.1.0/24) into complete subnet details.
It calculates:
- Network address
- Broadcast address
- Subnet mask
- Wildcard mask
- Total IP addresses
- First usable IP
- Last usable IP
- Usable host count
Use it for classic subnet planning, firewall configuration, IP range validation, and networking design.
It is especially handy when you already have a CIDR block and need to answer, quickly and accurately, “What does this subnet actually contain?”
Enter any IPv4 CIDR (e.g., 192.168.1.0/24) below to calculate network ranges and details.
What This CIDR Calculator Does
CIDR (Classless Inter-Domain Routing) allows flexible subnet sizing by defining how many bits are used for the network portion of an IP address.
Given a CIDR block, this tool:
- Determines the network address (first address in the subnet)
- Calculates the broadcast address (last address in the subnet)
- Converts the prefix to a subnet mask
- Computes the wildcard mask
- Calculates the total number of IP addresses
- Identifies the usable host range
This makes it useful for both beginners learning subnetting and experienced engineers validating IP ranges.
In practice, people often use a CIDR range calculator in three situations:
- during design, when comparing candidate subnet sizes
- during implementation, when verifying a route, ACL, or firewall object
- during troubleshooting, when checking whether an address really belongs inside a given subnet
Example: 10.0.0.0/24
CIDR: 10.0.0.0/24
- Network address: 10.0.0.0
- Broadcast address: 10.0.0.255
- Subnet mask: 255.255.255.0
- Total IP addresses: 256
- Usable hosts: 254
- Usable range: 10.0.0.1 – 10.0.0.254
A /24 subnet uses 24 bits for the network portion and leaves 8 bits for hosts, resulting in 256 total IP addresses.
That sounds simple, but this exact check prevents a lot of bad assumptions. Teams regularly mix up:
- total addresses vs usable hosts
- network boundary vs first usable IP
- classic IPv4 host counts vs cloud-usable counts
Understanding CIDR Notation
CIDR notation expresses an IP network using:
IP address / prefix length
Example:
/16→ 65,536 total addresses/24→ 256 total addresses/30→ 4 total addresses
The prefix length determines how many bits are reserved for the network.
The remaining bits define the host space.
Total addresses are calculated as:
2^(32 - prefix)
If you work with CIDR regularly, it is worth building intuition for a few common sizes:
/24feels small in cloud environments but is still common in on-prem networks/23doubles a/24/22gives enough space for many medium-sized environments/30is used when you need only a tiny point-to-point range
Network vs Broadcast Address
In traditional IPv4 subnetting:
- The network address identifies the subnet itself.
- The broadcast address is used to send traffic to all hosts within the subnet.
- These two addresses are typically not assignable to devices.
For example, in 192.168.1.0/24:
192.168.1.0→ network address192.168.1.255→ broadcast address
All assignable host IPs fall between those values.
This is one reason the tool is helpful in change reviews. If someone proposes a range that accidentally includes the network or broadcast address, you can catch it immediately.
How Engineers Actually Use a CIDR Range Calculator
Validate firewall and ACL objects
If someone gives you a rule for 10.50.8.0/21, it is not always obvious where that range ends without calculation. The tool shows the exact boundary so you can confirm the intended scope before applying access rules.
Check whether a host belongs in a subnet
If a server is configured with 10.0.7.14/22, the calculator helps verify the actual network, usable range, and whether nearby addresses are local or remote.
Sanity-check migration plans
During cutovers, teams often allocate temporary address ranges. A fast CIDR breakdown helps confirm that the proposed subnet does not overlap unexpectedly with an existing block.
Explain subnetting to others
The output is concrete enough to use in documentation, peer review, and onboarding conversations when someone is still learning how prefix lengths affect usable space.
When to Use This vs the Cloud Usable IP Calculator
This tool performs classic subnet math.
If you are working in Azure, AWS, or Google Cloud, cloud providers reserve additional IP addresses inside each subnet.
In those cases, use:
The cloud-aware calculator adjusts for provider-reserved IP addresses automatically.
That distinction matters. A /24 may look like 254 usable hosts in classic IPv4 math, but Azure and AWS reserve additional addresses inside the subnet. If your environment is cloud-first, the classic answer is not always the deployable answer.
CIDR Reference Table
| CIDR | Subnet Mask | Total IPs | Usable Hosts |
|---|---|---|---|
| /30 | 255.255.255.252 | 4 | 2 |
| /29 | 255.255.255.248 | 8 | 6 |
| /28 | 255.255.255.240 | 16 | 14 |
| /27 | 255.255.255.224 | 32 | 30 |
| /26 | 255.255.255.192 | 64 | 62 |
| /25 | 255.255.255.128 | 128 | 126 |
| /24 | 255.255.255.0 | 256 | 254 |
| /23 | 255.255.254.0 | 512 | 510 |
| /22 | 255.255.252.0 | 1024 | 1022 |
| /21 | 255.255.248.0 | 2048 | 2046 |
These counts are intentionally classic IPv4 values. They do not subtract provider-specific cloud reservations.
Frequently Asked Questions
Does this CIDR calculator support IPv6?
Not yet. This tool currently supports IPv4 only. An IPv6 subnet calculator is planned.
What is a wildcard mask?
A wildcard mask is the inverse of a subnet mask. It is commonly used in firewall and ACL configurations.
Can I enter a host IP instead of the network address?
Yes. The calculator automatically normalizes the network based on the prefix.
When should I use this instead of the subnet-splitting tool?
Use this page when you already have a CIDR and want the details for that one network. Use the subnet calculator when you need to divide a larger block into many smaller equal-size networks.
Does this calculator account for Azure, AWS, or GCP reserved addresses?
No. This page shows classic IPv4 subnet math. For provider-aware usable host counts, use the Cloud Usable IP Calculator.
Common Mistakes This Tool Helps Prevent
- Treating a host IP as if it were the subnet boundary
- Confusing total IP count with usable host count
- Writing firewall objects that exceed the intended range
- Forgetting that
/23and/22expand much more quickly than many people expect - Applying classic subnet math to a cloud subnet without accounting for reserved platform IPs