IP Subnet Calculator
Subnetting Made Simple - No Math Required
Results
Enter an IP address and select a subnet mask to see results.
What is IP Subnetting?
Subnetting is the practice of dividing a network into smaller network sections called subnets. This calculator helps you:
- Determine subnet masks and CIDR notation
- Calculate network and broadcast addresses
- Find the usable host IP range
- Plan efficient network address allocations
Key Subnetting Concepts
CIDR Notation: Classless Inter-Domain Routing (e.g., 192.168.1.0/24) specifies the network portion of an address.
Subnet Mask: A 32-bit number that masks an IP address and divides it into network and host portions.
Network Address: The first address in a subnet that identifies the network itself.
Broadcast Address: The last address in a subnet used to send data to all hosts.
How to Use the IP Subnet Calculator
- Enter IP Address: Type a valid IPv4 address in the IP Address field (e.g.,
192.168.1.1). - Select Subnet Mask: Choose the desired subnet mask from the dropdown list. The mask is shown in both dotted-decimal format and CIDR notation (e.g.,
255.255.255.0 (/24)). - Click Calculate: Press the Calculate button to generate detailed subnet information.
- View Results: The calculator will display:
- Network Address
- Broadcast Address
- Subnet Mask & CIDR
- Usable Host Range
- Total Number of Hosts
- Adjust & Recalculate: Change the IP address or subnet mask at any time and click Calculate again for updated results.
IP Address Structure Example
Frequently Asked Questions
An IP subnet calculator helps network administrators divide a network into smaller subnetworks (subnets). It calculates CIDR notation, subnet masks, network addresses, broadcast addresses, and host ranges.
IPv4 uses 32-bit addresses with subnet masks, while IPv6 uses 128-bit addresses with prefix lengths. IPv6 subnetting is simpler as it typically uses /64 prefixes for most networks.
The formula is 2^(host bits) - 2. For example, a /24 network has 8 host bits (32-24), so 2^8 - 2 = 254 usable hosts. Our calculator automatically computes this for any given subnet.
We subtract 2 because the first address is the network address and the last is the broadcast address, which cannot be assigned to hosts.
Network Subnetting Made Simple
Our IP subnet calculator provides instant results for all your network planning needs. Whether you're configuring a small office network or managing enterprise-level IP allocations, this tool helps you:
- Efficiently allocate IP addresses
- Prevent IP address conflicts
- Optimize network performance
- Plan for future network growth
- Understand complex subnetting concepts
Common Use Cases
Network engineers, system administrators, and IT students frequently use subnet calculators for:
- Configuring routers and firewalls
- Troubleshooting network connectivity
- Planning cloud infrastructure deployments
- Documenting network topologies