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IP Subnet Calculator

Calculate subnet masks, wildcard masks, and CIDR notation for any IPv4 or IPv6 network. Determine usable IP ranges, broadcast addresses, and network classes instantly.

IP Subnet Calculator

IP Subnet Calculator

Calculate Network Addresses, Subnet Masks, and IP Ranges Instantly

What is the IP Subnet Calculator?

The IP Subnet Calculator is a comprehensive, free online tool that performs all essential network subnetting calculations for both IPv4 and IPv6 addresses. Simply enter an IP address and subnet mask (or CIDR notation), and instantly receive detailed information including network address, broadcast address, usable host range, subnet mask, wildcard mask, and the number of available hosts.iptp+2​

Whether you're a network administrator planning IP address allocation, a system engineer configuring routers and switches, an IT professional studying for certifications, or a developer setting up network infrastructure, the CyberTools IP Subnet Calculator simplifies complex binary calculations and makes subnet planning fast and accurate.pandorafms+1​

How to Use the IP Subnet Calculator

Using our subnet calculator is simple and delivers instant results:solarwinds+1​

Step 1: Enter IP Address

Input the IP address you want to calculate:iptp+1​

  • IPv4 format: 192.168.1.100, 10.0.0.1, 172.16.5.50
  • IPv6 format: 2001:0db8:85a3::8a2e:0370:7334
  • With CIDR: 192.168.1.0/24 or 10.0.0.0/8geeksforgeeks+1​

Step 2: Specify Subnet Mask

Choose how to define the subnet mask:solarwinds+1​

CIDR Notation (Recommended):calculator+1​

  • Enter slash notation: /24, /16, /8, /28, etc.
  • Represents number of network bitscalculator​
  • Industry standard formatgeeksforgeeks​

Decimal Notation:

  • Traditional format: 255.255.255.0, 255.255.0.0
  • Converted automatically to CIDRiptp​

Subnet Bits:

  • Specify number of subnet bits borrowed from host portion
  • Used for custom subnet designsolarwinds​

Step 3: Select Network Class (IPv4)

For IPv4 addresses, optionally select class:iptp​

  • Class A: First octet 1-126 (8 network bits)calculator+1​
  • Class B: First octet 128-191 (16 network bits)calculator+1​
  • Class C: First octet 192-223 (24 network bits)iptp+1​

Auto-detection: Tool automatically identifies class from IP address.calculator​

Step 4: Calculate Subnets

Click "Calculate" to generate comprehensive results:solarwinds+1​

Network Information:

Subnet Mask Details:

  • Subnet Mask: Decimal notation (e.g., 255.255.255.0)calculator+1​
  • Wildcard Mask: Inverse of subnet mask (for Cisco ACLs)geeksforgeeks​
  • CIDR Notation: Prefix length (e.g., /24)calculator+1​
  • Binary Representation: Full 32-bit or 128-bit binary formatjodies+1​

Additional Information:

  • IP Class: A, B, C classification (IPv4)geeksforgeeks+1​
  • Network Type: Private or public IP rangecalculator​
  • Subnet Bits: Number of bits borrowed for subnettingsolarwinds​
  • Host Bits: Remaining bits for host addressescalculator​

What is Subnetting?

Subnetting is the practice of dividing a larger network into smaller, more manageable sub-networks (subnets). This improves network performance, enhances security, and enables efficient IP address utilization.thepowermba+2​

Why Subnet Networks?thepowermba​

Performance Optimization:

  • Reduces broadcast traffic in smaller segmentsthepowermba​
  • Improves network speed and efficiency
  • Limits congestion in individual subnets
  • Better bandwidth management

Security Enhancement:thepowermba​

  • Isolates different departments or functionsthepowermba​
  • Contains security breaches to single subnet
  • Implements granular access controls
  • Separates sensitive data networks

Efficient IP Management:pandorafms+1​

  • Maximizes use of available IP addressespandorafms​
  • Prevents IP address wastethepowermba​
  • Organizes address allocation logically
  • Simplifies network administrationpandorafms​

Organizational Structure:

  • Aligns network with business unitsthepowermba​
  • Separates departments logically
  • Geographic location organization
  • Function-based segmentation

How Subnetting Workscalculator​

IP addresses consist of two parts:calculator​

  1. Network Portion: Identifies the networkcalculator​
    • Determined by subnet mask
    • Shared by all hosts in subnet
    • Routes traffic to correct network
  2. Host Portion: Identifies individual devicecalculator​
    • Unique within the subnet
    • Assigned to network interfaces
    • Determines number of available hosts

Subnet mask determines the division between network and host portions by using binary 1s for network bits and 0s for host bits.calculator​

Example:


text
IP Address:    192.168.1.100
Subnet Mask:   255.255.255.0 (/24)

Binary IP:     11000000.10101000.00000001.01100100
Binary Mask:   11111111.11111111.11111111.00000000
               └──────── Network ─────────┘└─ Host ─┘

Network Address: 192.168.1.0
Host Address:    .100

Understanding CIDR Notationgeeksforgeeks+1​

CIDR (Classless Inter-Domain Routing) notation expresses subnet masks using a slash followed by the number of network bits.geeksforgeeks+1​

CIDR Formatcalculator​

Structure: IP_Address/Prefix_Length

Examples:

  • 192.168.1.0/24 = Subnet mask 255.255.255.0
  • 10.0.0.0/8 = Subnet mask 255.0.0.0
  • 172.16.0.0/16 = Subnet mask 255.255.0.0
  • 192.168.1.0/28 = Subnet mask 255.255.255.240

Common CIDR Prefixescalculator​

CIDRSubnet MaskUsable HostsNetwork Size/8 | 255.0.0.0 | 16,777,214 | Class A network calculator​
/16 | 255.255.0.0 | 65,534 | Class B network calculator​
/24 | 255.255.255.0 | 254 | Class C network calculator​
/25 | 255.255.255.128 | 126 | Half of /24 calculator​
/26 | 255.255.255.192 | 62 | Quarter of /24 calculator​
/27 | 255.255.255.224 | 30 | 8th of /24 calculator​
/28 | 255.255.255.240 | 14 | 16th of /24 calculator​
/29 | 255.255.255.248 | 6 | Point-to-point links calculator​
/30 | 255.255.255.252 | 2 | Point-to-point (common) calculator​
/31 | 255.255.255.254 | 2 | Point-to-point (RFC 3021) calculator​
/32 | 255.255.255.255 | 1 | Single host route calculator​





Calculating Hosts from CIDRcalculator​

Formula: Total Hosts = 2^(32 - prefix_length)calculator​

Example for /24:

  • Prefix: 24 bits for network
  • Host bits: 32 - 24 = 8 bits
  • Total addresses: 2^8 = 256
  • Usable hosts: 256 - 2 = 254calculator​

Why subtract 2? Network address and broadcast address cannot be assigned to hosts.geeksforgeeks+1​

IPv4 vs IPv6 Subnettingiptp+2​

IPv4 Subnettingcalculator​

Characteristics:

  • 32-bit addresses (4 octets)calculator​
  • Format: 192.168.1.1
  • Address space: ~4.3 billion addresses
  • Subnet mask: Expressed in decimal or CIDRcalculator​
  • Classes: A, B, C, D, Ecalculator​

IPv4 Subnet Calculation Example:


text
IP Address:     192.168.10.50/26
Subnet Mask:    255.255.255.192
Network Address: 192.168.10.0
Broadcast:      192.168.10.63
Usable Range:   192.168.10.1 - 192.168.10.62
Total Hosts:    64
Usable Hosts:   62

IPv6 Subnettingiptp+2​

Characteristics:

  • 128-bit addresses (8 groups of 4 hex digits)calculator​
  • Format: 2001:0db8:85a3::8a2e:0370:7334
  • Address space: 340 undecillion addresses
  • Default subnet: /64 for end networksiptp​
  • No broadcast: Uses multicast instead

IPv6 Subnet Calculation Example:


text
IP Address:     2001:db8::/32
Prefix Length:  /32
Network Prefix: 2001:0db8:0000:0000::/32
First Address:  2001:0db8:0000:0000:0000:0000:0000:0001
Last Address:   2001:0db8:ffff:ffff:ffff:ffff:ffff:fffe
Total /64 Networks: 4,294,967,296

IPv6 Subnetting Hierarchy:iptp​

  • /32: ISP allocation
  • /48: Organization/site allocation
  • /56: Home/small site allocation
  • /64: Default subnet (single network segment)iptp​

Understanding Calculation Results

Network Addressgeeksforgeeks+1​

The first address in a subnet where all host bits are zero.calculator​

Purpose:

Example: For 192.168.1.0/24, network address is 192.168.1.0

Broadcast Addressgeeksforgeeks+1​

The last address in a subnet where all host bits are one.calculator​

Purpose:

  • Sends data to all hosts in subnet simultaneouslycalculator​
  • Used for network announcements
  • Cannot be assigned to hostscalculator​
  • IPv4 only (IPv6 uses multicast)

Example: For 192.168.1.0/24, broadcast is 192.168.1.255

Usable Host Rangegeeksforgeeks+1​

IP addresses available for assignment to devices.geeksforgeeks​

Calculation:

Example: 192.168.1.0/24 = 192.168.1.1 through 192.168.1.254 (254 usable hosts)calculator​

Subnet Maskgeeksforgeeks+1​

32-bit number that separates network and host portions.calculator​

Formats:

How it works: Binary 1s represent network bits, 0s represent host bits.calculator​

Wildcard Maskgeeksforgeeks​

Inverse of subnet mask used primarily in Cisco router ACLs and OSPF configurations.geeksforgeeks​

Calculation: Subtract each octet of subnet mask from 255geeksforgeeks​

Example:


text
Subnet Mask:  255.255.255.0
Wildcard Mask: 0.0.0.255

Usage: access-list 10 permit 192.168.1.0 0.0.0.255 (Cisco IOS)

Common Subnetting Scenarios

Scenario 1: Office Network Divisionthepowermba​

Requirement: Divide 192.168.1.0/24 into 4 subnets for departments

Solution: Use /26 (255.255.255.192) - provides 4 subnets of 62 hosts eachcalculator​

Resulting Subnets:

  1. HR: 192.168.1.0/26 (192.168.1.1 - 192.168.1.62)
  2. Sales: 192.168.1.64/26 (192.168.1.65 - 192.168.1.126)
  3. IT: 192.168.1.128/26 (192.168.1.129 - 192.168.1.190)
  4. Finance: 192.168.1.192/26 (192.168.1.193 - 192.168.1.254)

Scenario 2: Point-to-Point Linkscalculator​

Requirement: Connect two routers with minimal IP waste

Solution: Use /30 (255.255.255.252) - provides exactly 2 usable hostscalculator​

Configuration:


text
Link: 10.0.0.0/30
Router A: 10.0.0.1
Router B: 10.0.0.2
Network: 10.0.0.0
Broadcast: 10.0.0.3

Scenario 3: Server Subnetthepowermba​

Requirement: 10 servers need isolation from user network

Solution: Use /28 (255.255.255.240) - provides 14 usable hostscalculator​

Network:


text
Subnet: 192.168.1.16/28
Range: 192.168.1.17 - 192.168.1.30
Hosts: 14 available (room for growth)

Common Use Cases

Network Administratorspandorafms​

Daily network management:

  • Planning IP address allocation schemespandorafms​
  • Designing VLAN IP rangespandorafms​
  • Calculating available addresses for growthpandorafms​
  • Optimizing network segmentationthepowermba​
  • Documenting network infrastructurepandorafms​
  • Troubleshooting routing issues

System Engineers

Infrastructure deployment:

  • Configuring router interfaces
  • Setting up switch VLANs
  • Planning datacenter networkspandorafms​
  • Designing DMZ subnetsthepowermba​
  • Implementing network security zonesthepowermba​
  • Multi-site network architecture

IT Certification Studentsiptp​

Exam preparation:

  • Studying for Cisco CCNA/CCNPiptp​
  • CompTIA Network+ practiceiptp​
  • Understanding binary conversionjodies+1​
  • Learning subnetting techniquesiptp​
  • Practicing subnet calculationsiptp​
  • Mastering CIDR notationgeeksforgeeks​

Cloud Architects

Cloud network design:

  • AWS VPC subnet planning
  • Azure Virtual Network configuration
  • Google Cloud network setup
  • Multi-tier application architecturethepowermba​
  • Hybrid cloud connectivity
  • Container network design

Security Professionalsthepowermba​

Network security:

ISP Engineers

Service provider operations:

  • Customer IP allocation
  • IPv6 deployment planning
  • Supernet aggregation
  • BGP route optimization
  • IP address management (IPAM)
  • Address block assignments

Features of CyberTools IP Subnet Calculator

✅ Dual Protocol Supportgeeksforgeeks+1​

  • IPv4 calculations – Complete supportgeeksforgeeks+1​
  • IPv6 calculations – Full 128-bit addressingiptp+1​
  • Mixed environments – Handle both protocolsgeeksforgeeks​
  • Auto-detection – Identifies IP version automatically

🔢 Multiple Input Formatsiptp+1​

Flexible entry methods:

  • CIDR notation (192.168.1.0/24)geeksforgeeks+1​
  • Decimal subnet mask (255.255.255.0)iptp​
  • Subnet bits specificationsolarwinds​
  • Class-based selection (A, B, C)iptp​

⚡ Instant Calculationssolarwinds​

  • Real-time results – Immediate outputsolarwinds​
  • No waiting – Sub-second processing
  • Unlimited calculations – Use as often as needed
  • Batch processing – Calculate multiple subnets

📊 Comprehensive Resultssolarwinds+1​

Complete network information:

🔧 Advanced Features

Professional tools:

  • Subnet planning – Design multiple subnetssolarwinds​
  • VLSM support – Variable Length Subnet Masking
  • Supernet calculation – Route aggregationjodies​
  • Binary converter – Decimal ↔ Binaryjodies+1​
  • Visual subnet maps – Graphical representation
  • Export results – PDF, CSV, JSON formats

📚 Educational Toolsjodies+1​

  • Binary visualization – See calculations in binarypandorafms+1​
  • Step-by-step explanations – Understand the math
  • Interactive learning – Practice subnettingiptp​
  • Random examples – Generate practice problemsiptp​
  • Tooltips and help – Contextual guidance
  • Certification prep – Exam-focused practiceiptp​

🔒 Privacy-Focused

  • No logging – Calculations not stored
  • Client-side processing – Data stays local
  • No registration – Anonymous use
  • Secure HTTPS – Encrypted connections
  • No tracking – Zero surveillance

📱 Mobile-Optimized

  • Responsive design – Works on all devices
  • Touch-friendly – Easy mobile input
  • Fast loading – Minimal bandwidth
  • Offline capable – Progressive web app
  • Copy-friendly – Easy result sharing

Best Practices for Subnettingpandorafms+1​

Planning and Designpandorafms+1​

✅ Plan for growth – Allocate more addresses than current needspandorafms​
✅ Document thoroughly – Maintain IP address management recordspandorafms​
✅ Use hierarchical design – Logical network structurethepowermba​
✅ Consider geography – Location-based subnet allocation
✅ Think security – Isolation of sensitive networksthepowermba​
✅ Standard subnet sizes – Consistency simplifies management

IP Address Allocationpandorafms​

✅ Reserve addresses – Keep ranges for special purposes
✅ Sequential assignment – Use IP addresses in order
✅ Avoid fragmentation – Contiguous address blockspandorafms​
✅ Plan for renumbering – Leave room for future changes
✅ Use private ranges – RFC 1918 for internal networks
✅ Document assignments – Track who uses whatpandorafms​

Security Considerationsthepowermba​

✅ Segment by function – Separate user, server, management networksthepowermba​
✅ Isolate sensitive data – Dedicated subnets for critical systemsthepowermba​
✅ Implement VLANs – Virtual network segmentationthepowermba​
✅ Limit broadcast domains – Smaller subnets reduce attack surfacethepowermba​
✅ DMZ architecture – Separate public-facing servicesthepowermba​
✅ Access controls – Firewall rules between subnetsthepowermba​

IPv6 Migration Planning

✅ Dual-stack networks – Run IPv4 and IPv6 simultaneously
✅ Use /64 for LANs – Standard IPv6 subnet sizeiptp​
✅ Hierarchical addressing – Leverage IPv6's vast space
✅ Document IPv6 scheme – Different from IPv4 thinking
✅ Test thoroughly – Verify application compatibility

Frequently Asked Questions

What's the difference between subnet mask and CIDR notation?

They represent the same thing in different formats:

Subnet Mask: Decimal notation (e.g., 255.255.255.0)calculator​
CIDR Notation: Prefix length (e.g., /24)geeksforgeeks+1​

Conversion examples:

CIDR is more concise and widely used in modern networking.geeksforgeeks​

Why can't I use the network and broadcast addresses?

Network address (all host bits = 0) identifies the network itselfcalculator​
Broadcast address (all host bits = 1) sends to all hostscalculator​

These are reserved functions, not assignable to individual devices. This is why usable hosts = total - 2.calculator​

Exception: /31 point-to-point links (RFC 3021) allow both addresses for routers.calculator​

How many subnets can I create from a network?

Formula: Number of subnets = 2^(borrowed bits)solarwinds​

Example: Starting with 192.168.1.0/24, borrowing 2 bits for subnets:

  • 2^2 = 4 subnets possiblesolarwinds​
  • Each subnet gets 6 host bits (2^6 = 64 addresses)
  • Result: Four /26 subnets with 62 usable hosts each

What is VLSM?

VLSM (Variable Length Subnet Masking) allows using different subnet mask lengths within the same network.

Benefits:

  • Efficient IP address utilizationpandorafms​
  • Customize subnet size to requirements
  • Reduce address wastethepowermba​
  • Better network design flexibility

Example:

  • Servers: /28 (14 hosts)
  • Users: /24 (254 hosts)
  • Point-to-point: /30 (2 hosts)calculator​

How do I calculate subnet mask from CIDR?

Convert CIDR prefix to subnet mask:

  1. Write prefix as binary 1s followed by 0s (total 32 bits)
  2. Convert to decimal octets

Example for /26:


text
Binary: 11111111.11111111.11111111.11000000
Decimal: 255.255.255.192

Or use our calculator for instant conversion.iptp+1​

What's the difference between public and private IP addresses?

Private IP Ranges (RFC 1918) – Not routable on internet:

  • 10.0.0.0 - 10.255.255.255 (/8)
  • 172.16.0.0 - 172.31.255.255 (/12)
  • 192.168.0.0 - 192.168.255.255 (/16)

Public IPs – Globally routable, must be unique worldwide

Use private IPs internally and NAT to public IP for internet access.

How does IPv6 subnetting differ from IPv4?

Key differences:iptp​

Address space:

Subnet size:

  • IPv4: Varies (/24, /26, /30, etc.)calculator​
  • IPv6: Typically /64 for end networksiptp​

Design philosophy:

  • IPv4: Conserve addressesthepowermba​
  • IPv6: Hierarchical allocation, no conservation needed

No broadcast: IPv6 uses multicast instead

What is a wildcard mask used for?

Wildcard masks are primarily used in:geeksforgeeks​

Cisco ACLs (Access Control Lists):


text
access-list 10 permit 192.168.1.0 0.0.0.255

OSPF area configuration:


text
network 10.0.0.0 0.255.255.255 area 0

Calculation: Inverse of subnet mask (255 - each octet)geeksforgeeks​

Example:

Related CyberTools for Network Management

Complement your subnet calculations with these related tools on CyberTools:

🌐 IP Information Tool

  • Lookup IP address details
  • Geographic location data
  • ISP and network information

🔍 WHOIS Lookup

  • IP block ownership information
  • Network registration details
  • Contact information for networks

🏓 Ping Tool

  • Test connectivity to subnet hosts
  • Verify network reachability
  • Measure latency within subnets

🔌 Open Port Checker

  • Test accessibility of subnet hosts
  • Verify firewall rules between subnets
  • Check service availability

📊 Bandwidth Calculator

  • Calculate network capacity requirements
  • Plan subnet bandwidth needs
  • Optimize network performance

🌍 Traceroute Tool

  • Map routing paths
  • Troubleshoot inter-subnet routing
  • Identify network bottlenecks

📝 Network Documentation Generator

  • Create subnet documentation
  • Export network diagrams
  • Generate IP allocation reports

Subnetting Formulas Quick Reference

Essential Calculations

Number of Subnets:


text
Subnets = 2^(borrowed bits)

Number of Hosts per Subnet:


text
Hosts = 2^(host bits) - 2

Subnet Size:


text
Size = 2^(32 - CIDR prefix)

Network Address:


text
IP AND Subnet Mask

Broadcast Address:


text
Network Address OR Wildcard Mask

Quick Subnet Referencecalculator​

CIDRHostsSubnets from /24/30 | 2 | 64 subnets calculator​
/29 | 6 | 32 subnets calculator​
/28 | 14 | 16 subnets calculator​
/27 | 30 | 8 subnets calculator​
/26 | 62 | 4 subnets calculator​
/25 | 126 | 2 subnets calculator​
/24 | 254 | 1 network calculator​





Start Calculating Subnets Now

Stop struggling with manual subnet calculations. Get instant, accurate results with the CyberTools IP Subnet Calculator.

✅ Completely free unlimited calculations
✅ IPv4 and IPv6 supportgeeksforgeeks+1​
✅ Multiple input formats – CIDR, decimal, bitsiptp+1​
✅ Instant results – Real-time calculationssolarwinds​
✅ Comprehensive information – All network detailsgeeksforgeeks+1​
✅ Binary visualization – See the mathpandorafms+1​
✅ Educational features – Learn while calculatingiptp​
✅ No registration required
✅ Export and share – Save your results

Calculate Subnets Now →

For network professionals: Need bulk subnet calculations or API access? Contact us about enterprise IPAM integration, automated subnet planning, and network documentation tools.

Have questions? Reach out at support@cybertools.cfd or visit our Contact Page.

The CyberTools IP Subnet Calculator helps thousands of network administrators, system engineers, IT students, and professionals plan and manage IP networks every day. Join them in simplifying complex subnet calculations and optimizing network design.

Related Resources:

  1. https://jodies.de
  2. https://pandorafms.com/blog/ip-calculator-networks/
  3. https://www.iptp.net/iptp-tools/ip-calculator/
  4. https://www.thepowermba.com/en/blog/subnetting-what-is-it
  5. https://www.geeksforgeeks.org/utilities/subnet-mask-calculator/
  6. https://www.solarwinds.com/free-tools/advanced-subnet-calculator
  7. https://www.calculator.net/ip-subnet-calculator.html
  8. https://pandorafms.com/blog/ip-subnet-calculator/
  9. https://www.subnetcalculator.dev/blog/ultimate-cheat-sheet-ip-range-calculations
  10. https://www.linux.com/topic/networking/how-calculate-network-addresses-ipcalc/


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