CIDR Block Subnet Calculator

Plan IPv4 networks faster. Decode ranges, masks, hosts, and broadcasts. Compare subnet options visually, export results, and validate addressing decisions easily.

Calculated Results

Results appear here after submission and stay above the calculator form.

Input IP
192.168.10.25
CIDR Prefix
/24
Subnet Mask
255.255.255.0
Wildcard Mask
0.0.0.255
Network Address
192.168.10.0
Broadcast Address
192.168.10.255
First Usable Host
192.168.10.1
Last Usable Host
192.168.10.254
Total Addresses
256
Usable Hosts
254
Address Type
Private
Address Class
Class C
Host Bits
8
Network Bits
24
Block Size
256
Network Decimal
3232238080
Broadcast Decimal
3232238335
Suggested Prefix for Subnet Count
/26
Suggested Prefix for Host Need
/26
Recommended Prefix
/26
Recommended Mask
255.255.255.192
Binary Views
IP: 11000000.10101000.00001010.00011001
Mask: 11111111.11111111.11111111.00000000
Network: 11000000.10101000.00001010.00000000
Wildcard: 00000000.00000000.00000000.11111111
Subnet Network Prefix First Host Last Host Broadcast Usable Hosts
1 192.168.10.0 /26 192.168.10.1 192.168.10.62 192.168.10.63 62
2 192.168.10.64 /26 192.168.10.65 192.168.10.126 192.168.10.127 62
3 192.168.10.128 /26 192.168.10.129 192.168.10.190 192.168.10.191 62
4 192.168.10.192 /26 192.168.10.193 192.168.10.254 192.168.10.255 62

Calculator

Reset

Example Data Table

Input IP Prefix Network First Host Last Host Broadcast Usable Hosts
192.168.10.25 /24 192.168.10.0 192.168.10.1 192.168.10.254 192.168.10.255 254
10.20.30.40 /20 10.20.16.0 10.20.16.1 10.20.31.254 10.20.31.255 4094
172.16.5.200 /27 172.16.5.192 172.16.5.193 172.16.5.222 172.16.5.223 30

Formula Used

The calculator uses standard IPv4 subnet math. A CIDR prefix determines how many bits belong to the network and how many remain for hosts.

Subnet mask from CIDR: mask = 2^32 - 2^(32 - prefix)

Network address: network = IP AND subnet mask

Broadcast address: broadcast = network + 2^(32 - prefix) - 1

Total addresses: 2^(32 - prefix)

Usable hosts: 2^(32 - prefix) - 2, except for /31 and /32.

Subnet recommendation: the tool compares the bits needed for requested subnet count and host requirement, then selects the tighter valid prefix.

How to Use This Calculator

Enter a valid IPv4 address in dotted decimal form, such as 192.168.10.25.

Set the CIDR prefix between 0 and 32 to define the network size.

Add the number of subnets you want if you are planning a subnet split.

Add the hosts needed per subnet to compare capacity requirements.

Click the calculate button to generate network details, binary views, and a subnet preview.

Review the result cards above the form, then export the outcome as CSV or PDF.

Use the chart to see how the chosen range compares with recommended subnetting options.

FAQs

1. What does CIDR mean?

CIDR stands for Classless Inter-Domain Routing. It replaces old fixed class boundaries and expresses network size with a slash prefix, such as /24. This makes address allocation and route aggregation more flexible.

2. What is the difference between total addresses and usable hosts?

Total addresses include every address in the block. Usable hosts usually exclude the network and broadcast addresses. The exception is /31 for point-to-point links and /32 for a single address.

3. Why is the network address important?

The network address identifies the entire subnet. Routers and switches use it for route decisions, summarization, and access control planning. It is not normally assigned to an end host.

4. Why is the broadcast address shown?

The broadcast address is the highest address in a traditional IPv4 subnet. It can be used to send traffic to all hosts on that subnet, although many modern networks limit broadcast-heavy designs.

5. How does the calculator recommend a subnet prefix?

It checks how many extra bits are needed to create the requested number of subnets and how many host bits are needed for each subnet. Then it chooses a prefix that satisfies both constraints.

6. Can this calculator detect private and public ranges?

Yes. It identifies common private, public, loopback, link-local, multicast, and reserved IPv4 blocks. That helps with quick validation when planning internal networks or checking internet-routable addressing.

7. What is a wildcard mask?

A wildcard mask is the inverse of the subnet mask. Network engineers often use it in access control lists and matching logic, because zero bits match exactly while one bits can vary.

8. Does this calculator support IPv6?

No. This version focuses on IPv4 subnetting only. The logic, formats, and address lengths for IPv6 are different, so a dedicated IPv6 calculator is better for accurate planning.

Related Calculators

classless subnet calculatorvlsm subnet calculatorsubnet prefix length calculatorsubnetting practice calculatornetwork address allocation calculatorvlsm block size calculatoripv4 vlsm calculatorip range subnet calculatorvariable length subnet calculatornetwork segmentation calculator

Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.