CIDR Calculator
Network, hosts & subnet masks
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CIDR Calculator
Network, hosts & subnet masks
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About this tool
Enter an IP with any /prefix and get the network, broadcast, host range, subnet/wildcard mask and host counts.
The CIDR and Subnet Calculator computes network and broadcast addresses, host ranges, subnet masks, and the number of available hosts for any CIDR notation (e.g., 192.168.1.0/24). It's an essential tool for network engineers, DevOps professionals, and cloud architects designing VPCs, allocating IP ranges, and planning subnet strategies for Kubernetes clusters and cloud infrastructure.
Enter any CIDR block and the calculator instantly shows the network address, first usable host, last usable host, broadcast address, wildcard mask, and total available hosts. It supports supernetting (CIDR aggregation) and subnetting (breaking a block into smaller subnets), displaying the resulting subnets in a clean table with their ranges — critical for AWS VPC planning, Kubernetes pod network allocation, and on-premise VLAN design.
The tool also includes a reverse lookup: enter a host IP address and a target subnet mask to determine which CIDR block it belongs to. All calculations are instant and client-side — your network topology and IP allocation data never leave your browser.
Key features
Everything you get with CIDR Calculator — no premium upsell.
Full CIDR block analysis: network, broadcast, host range, and available hosts
Subnet calculator: divide a block into smaller subnets with clear output
Supernetting: aggregate multiple CIDR blocks into a summary route
Reverse lookup: find the CIDR block for any IP address
Wildcard mask and subnet mask display in multiple formats
Client-side — network topology data never transmitted
How to use CIDR Calculator
Follow the steps below to use the tool.
- 1
Enter CIDR Block
Type any CIDR notation (e.g., 10.0.0.0/8 or 192.168.1.0/24) into the input field.
- 2
View Network Details
See the network address, first/last host, broadcast address, wildcard mask, and total available hosts instantly.
- 3
Calculate Subnets
Enter a desired new prefix length (e.g., split /24 into /26) to see all resulting subnets with their ranges.
- 4
Copy Results
Copy the subnet table or individual values for use in network configuration files, Terraform, or documentation.
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