Productive ToolboxCIDR Calculator
Calculate CIDR notation details including network address, broadcast, subnet mask, wildcard mask, usable hosts, IP range, and binary representation for any IPv4 address instantly.
IPv4 CIDR Calculator
Enter an IPv4 address with CIDR prefix (e.g. 192.168.1.1/24) to instantly calculate network address, broadcast, host range, and more. We do not collect or store what you enter.
Input
Press Esc to reset
CIDR Summary
Quick Presets
Calculation Results
Related tools
How to Use the CIDR Calculator
Quick Start Guide
- 1Enter the IP and prefix: Type an IPv4 address with its CIDR prefix, such as 192.168.1.1/24, or switch to Manual mode to enter the IP address and subnet mask separately.
- 2Adjust the prefix: Use the slider or the quick-select buttons (/8, /16, /24, /28 …) to change the prefix length.
- 3Read the results: The network address, broadcast address, usable host range, subnet and wildcard masks, IP class and address type update as you type.
- 4Copy, export or share: Copy the summary, download it as TXT or JSON, or share a link that opens the same calculation.
Key Features
- ✓Real-time CIDR calculation as you type
- ✓CIDR notation and subnet mask input modes
- ✓CIDR ↔ subnet mask auto-conversion
- ✓Quick CIDR preset buttons (/8 to /32)
- ✓CIDR prefix slider for fast adjustments
- ✓Binary visualization of IP, mask, and network
- ✓Private / public / loopback / multicast detection
- ✓IP class detection (A, B, C, D, E)
- ✓Shareable URL with ip + cidr parameters
- ✓Calculation history saved in browser
- ✓Export results as TXT or JSON
- ✓Copy full summary to clipboard
Example CIDR Calculations
| Input | Network | Broadcast | Usable Range | Usable Hosts |
|---|---|---|---|---|
| 192.168.1.1/24 | 192.168.1.0 | 192.168.1.255 | 192.168.1.1 – 192.168.1.254 | 254 |
| 10.0.0.1/16 | 10.0.0.0 | 10.0.255.255 | 10.0.0.1 – 10.0.255.254 | 65,534 |
| 172.16.50.10/28 | 172.16.50.0 | 172.16.50.15 | 172.16.50.1 – 172.16.50.14 | 14 |
| 10.10.0.1/30 | 10.10.0.0 | 10.10.0.3 | 10.10.0.1 – 10.10.0.2 | 2 |
| 8.8.8.8/24 | 8.8.8.0 | 8.8.8.255 | 8.8.8.1 – 8.8.8.254 | 254 |
CIDR & Subnet Mask Reference
| CIDR | Subnet Mask | Wildcard | Total Addresses | Usable Hosts |
|---|---|---|---|---|
| /8 | 255.0.0.0 | 0.255.255.255 | 16,777,216 | 16,777,214 |
| /16 | 255.255.0.0 | 0.0.255.255 | 65,536 | 65,534 |
| /24 | 255.255.255.0 | 0.0.0.255 | 256 | 254 |
| /25 | 255.255.255.128 | 0.0.0.127 | 128 | 126 |
| /26 | 255.255.255.192 | 0.0.0.63 | 64 | 62 |
| /27 | 255.255.255.224 | 0.0.0.31 | 32 | 30 |
| /28 | 255.255.255.240 | 0.0.0.15 | 16 | 14 |
| /29 | 255.255.255.248 | 0.0.0.7 | 8 | 6 |
| /30 | 255.255.255.252 | 0.0.0.3 | 4 | 2 |
| /31 | 255.255.255.254 | 0.0.0.1 | 2 | 2 (P2P) |
| /32 | 255.255.255.255 | 0.0.0.0 | 1 | 1 (host) |
Frequently Asked Questions
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation writes an IP address with the length of its network prefix. In 192.168.1.0/24, the first 24 bits identify the network and the remaining 8 bits identify hosts. CIDR replaced the old class A/B/C system so networks can be any size.
How is the network address calculated?
By a bitwise AND of the IP address and the subnet mask. For 192.168.1.25/24 the mask is 255.255.255.0, so the network address is 192.168.1.0.
What is the broadcast address?
The last address in the subnet: the network address with every host bit set to 1 (a bitwise OR with the wildcard mask). A packet sent to it reaches every host on the subnet. For 192.168.1.0/24 it is 192.168.1.255.
How many usable hosts does a /24 have?
A /24 has 2^8 = 256 addresses. The network and broadcast addresses are reserved, leaving 254 usable hosts. In general a prefix from /1 to /30 has 2^(32 − prefix) − 2 usable hosts.
What are /31 and /32 subnets used for?
A /31 has two addresses, both usable, for point-to-point links between routers (RFC 3021). A /32 is a single address, used for loopback interfaces, host routes and firewall rules that match one IP.
What is a wildcard mask?
The bitwise inverse of the subnet mask: it marks the host bits. For /24 (255.255.255.0) the wildcard mask is 0.0.0.255. Cisco access lists and OSPF network statements use wildcard masks.
Does the calculator support IPv6?
No, it works with IPv4 addresses only. IPv6 uses 128-bit addresses and a /64 is the standard subnet size, so IPv4 host counts and broadcast addresses do not apply.
Who Uses CIDR Calculators?
Network Engineers
Plan IP addressing, VLAN segmentation, and route summarization for enterprise and carrier networks.
Cloud Engineers
Design VPC CIDR blocks, subnet splits, and security group rules for AWS, Azure, and GCP infrastructure.
Security Professionals
Configure firewall ACLs, network segmentation, and zero-trust architecture using CIDR ranges.
Certification Students
Practice subnetting for CCNA, Network+, AWS Solutions Architect, and other networking certifications.
DevOps Engineers
Define Terraform, CloudFormation, and Ansible network configurations with precise CIDR blocks.
System Administrators
Manage DHCP scopes, static IP assignments, and troubleshoot IP conflicts across server infrastructure.
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