Subnet Calculator Online Free
Compute IPv4 subnet structures instantly. Enter a base IP address and CIDR prefix length to calculate network masks, broadcast points, usable host counts, and network boundaries.
✓ Free IT tool✓ No signup required✓ Fast results✓ Browser-based utility✓ Mobile friendly
Invalid CIDR notation. Use format: 192.168.1.0/24
This tool runs in your browser and does not upload data to BuBird servers.
How To Use
How to Use Subnet Calculator
1
Provide Base IP Address
Type the base IPv4 address (e.g., 192.168.1.1) into the target input field.
2
Choose Subnet Prefix Length
Select the CIDR suffix prefix (e.g., /24) from the dropdown or input scale.
3
Inspect Subnet Details
The calculations resolve instantly. Observe network mask, broadcast address, and host quantities.
4
Copy Target Ranges
Copy calculated ranges for your router settings, virtual machines, or local setups.
Example
Example Use
Planning IP Allocation for a New VLAN
To provision a new departmental network segment supporting up to 50 active host systems, enter a private IP (e.g., 10.0.5.0) and choose prefix /26. The calculator indicates that this provides 62 usable host addresses, with network address 10.0.5.0 and usable range 10.0.5.1 to 10.0.5.62.
Use Cases
Who Uses Subnet Calculator
Network Architects
Plan host partitioning, routing protocols, and address layouts.
Cloud Architects
Provision AWS VPCs, Azure VNets, and GCP subnets cleanly.
SysAdmins
Configure server static IPs and network gateways securely.
IT Students
Learn binary IP arithmetic, bitmask calculations, and routing theory.
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FAQ
Frequently Asked Questions
What is subnetting?
Subnetting is the practice of dividing a larger physical network into smaller, logical sub-networks (subnets) to improve performance, routing management, and network security.
What details does this calculator provide?
Entering an IP and CIDR gives you the subnet mask, network address, broadcast address, first usable IP, last usable IP, and total number of usable host hosts.
Does this tool support IPv6?
This subnet calculator is dedicated to IPv4 notation calculations, which use standard dot-decimal values.