IP Subnet Calculator

IP Subnet Calculator

Calculate subnet information, network ranges, and host addresses. Essential tool for network administrators and IT professionals.

Common Subnet Masks

Network Classes

Network Configuration

Enter IP address (e.g., 192.168.1.1)

Enter subnet mask (e.g., 255.255.255.0)

CIDR Notation

Enter CIDR prefix (e.g., /24)

Input Summary

IP Address: Not specified
Subnet Mask: Not specified
CIDR: Not specified
Valid IP: N/A

About IP Subnet Calculator

Our comprehensive IP subnet calculator helps network administrators and IT professionals understand and manage IP addressing schemes. This essential networking tool provides accurate subnet calculations, network ranges, and host addressing information for efficient network design and management.

What It Calculates

  • Network Address: First address in the subnet
  • Broadcast Address: Last address in the subnet
  • Host Range: Usable IP addresses in the subnet
  • Subnet Mask: Network portion identification
  • CIDR Notation: Modern prefix length notation
  • Host Count: Total and usable host addresses

Network Classes

Class A

1.0.0.0 - 126.255.255.255

Class B

128.0.0.0 - 191.255.255.255

Class C

192.0.0.0 - 223.255.255.255

How to Use

Enter an IP address and either a subnet mask or CIDR notation. The calculator automatically computes the network address, broadcast address, first and last usable host addresses, and provides detailed subnet information including total and usable host counts.

Pro Tip

When planning your network, always consider future growth and scalability. Use subnetting to create logical network segments that match your organizational structure. Remember that the network address and broadcast address are reserved and cannot be assigned to hosts. Document your subnet plan thoroughly for troubleshooting and network management.

About IP Subnet Calculator

Our comprehensive IP subnet calculator helps network administrators and IT professionals understand and manage IP addressing schemes. This essential networking tool provides accurate subnet calculations, network ranges, and host addressing information for efficient network design and management.

What It Calculates

  • Network Address: First address in the subnet
  • Broadcast Address: Last address in the subnet
  • Host Range: Usable IP addresses in the subnet
  • Subnet Mask: Network portion identification
  • CIDR Notation: Modern prefix length notation
  • Host Count: Total and usable host addresses

IP Addressing Fundamentals

IPv4 Address Structure
  • 32-bit Address: 4 octets of 8 bits each
  • Dotted Decimal: 192.168.1.1 format
  • Network Portion: Identifies the network
  • Host Portion: Identifies specific devices
  • Classful Addressing: A, B, C, D, E classes
  • Classless Addressing: CIDR and VLSM
Subnet Mask Purpose
  • Network Separation: Divides networks logically
  • Traffic Control: Determines routing decisions
  • Security: Isolates network segments
  • Efficiency: Optimizes network performance
  • Scalability: Supports network growth
  • Management: Simplifies network administration

Understanding Your Results

Network Address

Subnet identifier

Broadcast Address

All hosts destination

Host Range

Usable addresses

Subnet Mask

Network boundary

How to Use

Enter an IP address and either a subnet mask or CIDR notation. The calculator automatically computes the network address, broadcast address, first and last usable host addresses, and provides detailed subnet information including total and usable host counts.

Network Classes and Ranges

Class A Networks:

  • Range: 1.0.0.0 - 126.255.255.255
  • Default Mask: 255.0.0.0
  • Hosts: 16,777,214 per network
  • Use: Large organizations
  • First Bit: 0
  • Examples: 10.0.0.0, 172.16.0.0

Class B Networks:

  • Range: 128.0.0.0 - 191.255.255.255
  • Default Mask: 255.255.0.0
  • Hosts: 65,534 per network
  • Use: Medium organizations
  • First Bits: 10
  • Examples: 172.16.0.0, 192.168.0.0

CIDR and Subnetting

CIDR Notation
  • Format: IP/prefix_length
  • Example: 192.168.1.0/24
  • Prefix Length: Number of network bits
  • Advantages: More flexible than classful
  • VLSM Support: Variable length subnet masks
  • Modern Standard: Current networking practice
Subnetting Benefits
  • Network Efficiency: Better resource utilization
  • Traffic Management: Reduced broadcast domains
  • Security: Isolated network segments
  • Performance: Optimized routing
  • Scalability: Support for growth
  • Management: Easier administration

Common Subnet Masks

  • /24 (255.255.255.0): 256 addresses, 254 usable hosts
  • /25 (255.255.255.128): 128 addresses, 126 usable hosts
  • /26 (255.255.255.192): 64 addresses, 62 usable hosts
  • /27 (255.255.255.224): 32 addresses, 30 usable hosts
  • /28 (255.255.255.240): 16 addresses, 14 usable hosts
  • /29 (255.255.255.248): 8 addresses, 6 usable hosts

Network Address Calculation

Binary Method
  • Convert to Binary: IP and mask to binary
  • AND Operation: IP AND mask = network
  • Convert Back: Binary result to decimal
  • Accuracy: 100% precise calculation
  • Complexity: Requires binary knowledge
  • Use Case: Manual verification
Decimal Method
  • Octet Analysis: Work with each octet
  • Mask Application: Apply mask to IP
  • Network Result: Direct decimal calculation
  • Speed: Faster than binary
  • Understanding: Easier to comprehend
  • Use Case: Quick calculations

Broadcast Address Calculation

  • Network Address: Start with calculated network address
  • Host Bits: Set all host bits to 1
  • Result: Broadcast address for the subnet
  • Purpose: Sends traffic to all hosts
  • Limitation: Cannot be assigned to hosts
  • Example: 192.168.1.0/24 → 192.168.1.255

Host Address Range

  • First Host: Network address + 1
  • Last Host: Broadcast address - 1
  • Usable Range: First to last host addresses
  • Reserved Addresses: Network and broadcast
  • Host Count: 2^host_bits - 2
  • Example: 192.168.1.1 - 192.168.1.254

Subnet Calculation Tips

  • Verify Input: Ensure valid IP address format
  • Check Mask: Validate subnet mask values
  • Consider Growth: Plan for future expansion
  • Document Results: Keep subnet information
  • Test Connectivity: Verify network communication
  • Follow Standards: Use industry best practices

Common Subnetting Mistakes

  • Wrong Network Address: Incorrect calculation
  • Invalid Host Range: Including reserved addresses
  • Mask Confusion: Wrong subnet mask
  • Overlap Issues: Subnets that conflict
  • Size Mismatch: Too many or too few hosts
  • Documentation Errors: Incorrect network records

Advanced Subnetting Concepts

  • Variable Length Subnet Masking (VLSM): Different subnet sizes
  • Route Summarization: Combining multiple subnets
  • Supernetting: Creating larger networks
  • Private IP Ranges: RFC 1918 address spaces
  • NAT Implementation: Network address translation
  • IPv6 Planning: Future network considerations
Pro Tip

When planning your network, always consider future growth and scalability. Use subnetting to create logical network segments that match your organizational structure. Remember that the network address and broadcast address are reserved and cannot be assigned to hosts. Document your subnet plan thoroughly, including network addresses, subnet masks, and host ranges. This documentation will be invaluable for troubleshooting and network management. Consider using private IP address ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) for internal networks to avoid conflicts with public addressing.