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IP Distance

Calculate number of addresses between two IPs (IPv4/IPv6).

About This Tool

The IP Distance Calculator computes the number of IP addresses between two endpoints, essential for network planning, range validation, and IP address arithmetic. This tool supports both IPv4 and IPv6, handles forward and reverse directions automatically, and offers inclusive or exclusive counting modes. Whether you're calculating DHCP pool sizes, verifying subnet boundaries, or determining how many addresses separate two IPs, this calculator provides instant results with clear directional indicators and big integer support for massive IPv6 ranges.

How to Use

  1. Enter two IP addresses in the format: start_ip -> end_ip
  2. Example: 192.168.0.1 -> 192.168.0.5 or 2001:db8::1 -> 2001:db8::10
  3. Both IPs must be the same version (both IPv4 or both IPv6)
  4. Check "Inclusive" to count both endpoints (distance includes start and end)
  5. Uncheck "Inclusive" for exclusive counting (endpoints not counted)
  6. Click "Calculate" to compute the distance
  7. Results show distance, direction (forward/backward), and IP version
  8. The tool handles any order - start can be greater than end

Features

  • IPv4 and IPv6 address distance calculation
  • Automatic forward/backward direction detection
  • Inclusive mode: counts both start and end IPs
  • Exclusive mode: counts only addresses between endpoints
  • Big integer arithmetic for IPv6 ranges
  • Clear directional indicators (forward/backward)
  • Version mismatch detection and validation
  • Handles reversed input order gracefully
  • Supports extremely large IPv6 ranges
  • Clear error messages for invalid inputs

Common Use Cases

  • DHCP pool size calculation and validation
  • Verifying IP allocation ranges in spreadsheets
  • Network capacity planning and IP inventory
  • Calculating addresses consumed in a subnet
  • Validating IP address ranges in configurations
  • Determining space between reserved blocks
  • Subnet fragmentation analysis
  • IP address auditing and compliance checks
  • Testing IP range logic in applications
  • Documentation and network diagrams

Technical Details

The IP Distance Calculator performs arithmetic operations on IP addresses, treating them as large integers and computing the numerical difference between two addresses.

Counting Modes:

  • Inclusive: Distance includes both start and end addresses (count = end - start + 1)
  • Exclusive: Distance excludes endpoints, counting only addresses between them (count = end - start - 1)
  • Example: 192.168.0.1 → 192.168.0.5 (Inclusive: 5, Exclusive: 3)

IPv4 Examples (Inclusive Mode):

  • 192.168.0.1 → 192.168.0.1: Distance = 1 (same address)
  • 192.168.0.1 → 192.168.0.5: Distance = 5 (addresses: .1, .2, .3, .4, .5)
  • 10.0.0.0 → 10.0.0.255: Distance = 256 (full /24 subnet)
  • 192.168.0.0 → 192.168.255.255: Distance = 65,536 (full /16 subnet)

IPv4 Examples (Exclusive Mode):

  • 192.168.0.1 → 192.168.0.5: Distance = 3 (addresses: .2, .3, .4)
  • 192.168.0.1 → 192.168.0.2: Distance = 0 (no addresses between adjacent IPs)
  • 10.0.0.0 → 10.0.0.255: Distance = 254 (usable host addresses in /24)

IPv6 Examples (Inclusive Mode):

  • 2001:db8::1 → 2001:db8::5: Distance = 5
  • 2001:db8:: → 2001:db8::ffff: Distance = 65,536
  • fe80:: → fe80::ffff:ffff:ffff:ffff: Distance = 2^64 (18,446,744,073,709,551,616)

Direction Detection:

The tool automatically detects whether you're counting forward or backward:

  • Forward: Start IP < End IP (natural order)
  • Backward: Start IP > End IP (reverse order)
  • Distance is always positive, regardless of direction
  • Example: 192.168.0.5 → 192.168.0.1 still shows distance = 5, marked as "backward"

Calculation Method:

  1. Convert both IP addresses to numerical representation (32-bit for IPv4, 128-bit for IPv6)
  2. Compute absolute difference: |end - start|
  3. If inclusive mode: add 1 to include both endpoints
  4. If exclusive mode: subtract 1 to exclude endpoints
  5. Return result with direction indicator

Use Cases for Inclusive vs. Exclusive:

  • Inclusive: Counting total IPs in a range (including boundaries)
  • Exclusive: Counting usable host addresses (excluding network/gateway/broadcast)
  • DHCP pools: Often exclusive (gateway and broadcast excluded)
  • Subnet size: Inclusive (network address to broadcast address)

Large IPv6 Ranges:

IPv6 subnets can be astronomically large. This tool uses big integer arithmetic to handle ranges like:

  • /64 subnet: 2^64 = 18,446,744,073,709,551,616 addresses
  • /48 allocation: 2^80 = 1,208,925,819,614,629,174,706,176 addresses
  • Results displayed in decimal notation for readability

Common Practical Examples:

  • DHCP pool verification: 192.168.1.10 → 192.168.1.200 = 191 IPs (inclusive)
  • Usable hosts in /24: .1 → .254 = 254 addresses (exclusive: 252 hosts)
  • Reserved block gap: 10.0.0.100 → 10.0.1.0 = 157 IPs between blocks
  • Adjacent addresses: .1 → .2 = 2 (inclusive) or 0 (exclusive)

Error Handling:

  • Version mismatch: "Cannot calculate distance between IPv4 and IPv6"
  • Invalid IP format: Clear parse error messages
  • Missing endpoint: "Both start and end IPs required"

Relationship to Other Tools:

  • CIDR Calculator: Computes size implicitly (2^(32-prefix) for IPv4)
  • IP Range Enumerator: Lists all addresses, distance shows count
  • Nth IP Calculator: Uses distance to validate index bounds