Calculate IPv4 subnets, CIDR notation, netmasks, broadcast addresses, and host ranges. Essential tool for network engineers.
What is Subnet Calculator?
The Subnet Calculator is a critical tool for network administrators and IT students. It simplifies the complex math involved in subnetting—the process of dividing a network into smaller, manageable sub-networks. By entering an IP address and a CIDR block (e.g., /24) or Subnet Mask, this tool instantly calculates the Network Address, Broadcast Address, First and Last Usable Host IP, and the total number of usable hosts. It helps prevent IP conflicts and ensures efficient network design.
Input Formats
IP Address (IPv4)
CIDR Suffix (0-32)
Subnet Mask
Output Results
Network Address
Broadcast Address
Usable Host Range
Total Hosts
Wildcard Mask
Key Features
Full Network Details: Calculates Network, Broadcast, and Host Range
CIDR Support: Intuitive selector for /24, /30, and all masks
Binary View: Visualizes how IP bits correspond to the subnet mask
Privacy: 100% Client-side processing
Capacity Planning: Instantly see the total usable hosts
Network Design: Essential for planning LANs and VPCs
Wildcard Mask: Automatically calculates the wildcard for ACLs
Best & Modern: The best modern subnet calculator for network engineers
Shareable LinksShare the subnet calculation. (Limit: 1KB)
Who is this for?
Network Setup
Planning a new office network and determining how many devices can fit in a subnet.
Network planningIP allocationLAN setup
Exam Prep
Studying for CCNA or CompTIA Network+ certification.
CCNA toolSubnetting practiceNetwork study
Cloud Config
Configuring VPC subnets in AWS, Azure, or Google Cloud.
VPC subnetCloud networkCIDR block
How to Use
1
Enter an IP address (e.g., 192.168.1.1).
2
Select the CIDR suffix (e.g., /24) or Subnet Mask.
3
View the calculated network details instantly.
Frequently Asked Questions
What is CIDR?
It stands for Classless Inter-Domain Routing. It's the /24 part that tells you how big the network is.
What is a Subnet Mask?
It's a filter that splits an IP address into 'Network' and 'Host' parts.
How many hosts are in a /24?
254 usable hosts. (256 total - 1 for network - 1 for broadcast).
What is the Broadcast Address?
It's the address used to shout a message to everyone on the network at once.
Does it support IPv6?
Not yet! I'm focusing on IPv4 right now since it's still the most common for local networks.
What is a Wildcard Mask?
It's the opposite of a subnet mask. Network engineers use it for firewall rules (ACLs).
