Real-Time Engine RFC 1918 • RFC 3021 • RFC 4291 Compliant

Network Calculator & Subnet Planner

Precision IPv4 CIDR breakdown, variable-length subnet mask (VLSM) partitioning, interactive 32-bit binary octet visualizer, IPv6 prefix tooling, and route summarization.

IPv4 Parameters

Enter an IP address and select a subnet mask or slide the CIDR prefix bar.

Valid IPv4 Address

IPv4 Host or Network Address

Supports CIDR notation directly (e.g. typing 10.0.0.1/22 auto-adjusts CIDR).

Subnet Mask / CIDR Prefix

Includes RFC 3021 /31 point-to-point and /32 single host definitions.

CIDR Prefix Slider (/0 to /32) /24

/0 /32

Quick Network Presets:

Usable Host Capacity 100%

254

Total Block: 256 IPs

Network ID

192.168.1.0/24

Broadcast: 192.168.1.255

Usable Host Range

192.168.1.1 – 192.168.1.254

First: 192.168.1.1 • Last: 192.168.1.254

Subnet & Scope Class C

255.255.255.0

Wildcard: 0.0.0.255

32-Bit Binary Octet Inspector

Visualizing network routing prefix vs host allocation bits across all 4 octets.

Network Bits (24 bits)

Host Bits (8 bits)

Octet 1192

11000000

Octet 2168

10101000

Octet 31

00000001

Octet 450

00110010

Subnet Architecture & Routing Matrix

RFC Standards Compliant

IP Address (Decimal & Hex) 192.168.1.50 • 0xC0A80132

Network ID & CIDR 192.168.1.0/24

Subnet Mask & Wildcard 255.255.255.0 • 0.0.0.255

Usable Host Range 192.168.1.1 – 192.168.1.254

Broadcast Address 192.168.1.255

Address Classification & RFC Scope Private Network (RFC 1918 - 192.168.0.0/16)

Reverse DNS PTR (RFC 1035) 50.1.168.192.in-addr.arpa

Cisco IOS Route Syntax ip route 192.168.1.0 255.255.255.0 [next-hop-ip/interface]

Summary of What Was Built — IPv4 Subnet & CIDR Calculator

Real-time reactive calculation engine, 32-bit binary visualizer, and routing breakdown

Feature Set Verified

Live Reactive Subnet Engine

Instantaneous recalculation on input typing or CIDR slider dragging (0ms latency), backed by server-side PHP processing for shareable URLs (?ip=...&cidr=...).

Real-Time Stat Cards Grid

Glanceable metrics displaying Usable Host Capacity, Total Block Size ($2^{32-p}$), Network ID, Broadcast Address, First & Last Usable IP bounds, Subnet Mask, and Inverted Wildcard.

32-Bit Binary Octet Inspector

Interactive bit visualizer across all 4 octets clearly differentiating Network routing prefix bits (Cyan) and Host allocation bits (Purple) with interactive bit tooltips.

Routing & Architecture Matrix

Automated computation of 32-bit Hex (0x...), IP Class (A–E), RFC scope (RFC 1918, CGNAT, APIPA, Loopback, Public), Reverse DNS PTR (in-addr.arpa), and Cisco IOS syntax with one-click copy.

One-Click Presets & RFC Standards

Instant chip presets for Office LAN (/24), VPC Core (/16), Data Center (/20), CGNAT (/24), P2P Link (/30), RFC 3021 modern point-to-point (/31), and Loopback (/8).

Subnet Partitioning & VLSM Allocation

Split any parent network block into uniform child subnets or plan custom capacities.

Parent Network ID

Parent CIDR Prefix

Subdivide Into Child CIDR

Subnet	Network CIDR	Subnet Mask	Usable IP Range	Broadcast	Usable Hosts
#1	192.168.1.0/26	255.255.255.192	192.168.1.1 – 192.168.1.62	192.168.1.63	62 hosts
#2	192.168.1.64/26	255.255.255.192	192.168.1.65 – 192.168.1.126	192.168.1.127	62 hosts
#3	192.168.1.128/26	255.255.255.192	192.168.1.129 – 192.168.1.190	192.168.1.191	62 hosts
#4	192.168.1.192/26	255.255.255.192	192.168.1.193 – 192.168.1.254	192.168.1.255	62 hosts

Showing 4 of 4 generated subnets.

Summary of What Was Built — Subnet Divider (VLSM Planner)

Variable-length subnet partitioning, allocation table generation, and data export

Feature Set Verified

Variable-Length Subnetting (VLSM)

Automatically subdivides any parent network block into uniform child subnets based on target CIDR prefix or required subnet capacity without IP address overlaps.

Subnet Allocation Table

Generates a structured partition matrix showing Subnet Index, Network CIDR, Subnet Mask, Usable IP Range, Broadcast Address, and Usable Host Capacity per partition.

Export & Portability Options

Direct one-click copy for individual subnet CIDRs, whole-table copy to clipboard, and automated CSV export (newhousenet_subnets_plan.csv).

Parent-Child Bidirectional Sync

Automatically updates parent network ID and CIDR when changes are made in the primary IPv4 tab, keeping your planning session completely synchronized.

IPv6 Architecture & Prefix Inspector

RFC 4291 address formatting, zero-compression, full 128-bit expansion, and PTR generation.

IPv6 Address (Compressed or Expanded)

Routing Prefix Length

IPv6 Presets

Compressed Notation (RFC 5952) 2001:db8:85a3::8a2e:370:7334

Fully Expanded 128-Bit Form 2001:0db8:85a3:0000:0000:8a2e:0370:7334

Subnet Prefix Network 2001:db8:85a3::/64

Address Scope & Type Documentation Prefix (2001:db8::/32)

Reverse DNS PTR (RFC 3596) 4.3.3.7.0.7.3.0.e.2.a.8.0.0.0.0.0.0.0.0.3.a.5.8.8.b.d.0.1.0.0.2.ip6.arpa

Summary of What Was Built — IPv6 Prefix & Tooling

RFC 4291/5952 compression, 128-bit expansion, scope analysis, and reverse PTR

Feature Set Verified

RFC 5952 Zero-Compression & Expansion

Automatically formats IPv6 addresses into standard canonical compressed format (collapsing zero runs with ::) and full 128-bit 8-hextet expanded notation.

Prefix Network Boundaries

Calculates network prefix base addresses and routing boundaries across standard allocation lengths (/128, /64 SLAAC, /56, /48, /32).

Address Scope & Type Detection

Identifies Global Unicast (2000::/3), Link-Local (fe80::/10), Unique Local ULA (fc00::/7), Multicast (ff00::/8), Loopback, and Documentation.

RFC 3596 IPv6 Reverse DNS PTR

Instantly generates 32-nibble dot-separated reverse DNS PTR records ending in .ip6.arpa ready for DNS zone deployment.

IP Range to CIDR Blocks

Convert an arbitrary IP address span into minimal aggregated CIDR subnets.

Start IPv4 Address

End IPv4 Address

Aggregated CIDR Summary:

192.168.1.1/32 192.168.1.2/31 192.168.1.4/30 192.168.1.8/29 192.168.1.16/28 192.168.1.32/27 192.168.1.64/27 192.168.1.96/30 192.168.1.100/32

Network Transfer Time Estimator

Estimate time required to transfer backups, images, or replication streams across link speeds.

Data Volume Size

Unit

Network Uplink Speed

Estimated Transfer Duration

6m 40s

Approx. 400.00 Gb at effective 1.00 Gbps line rate.

Summary of What Was Built — Route Summarizer & Bandwidth Estimator

IP range aggregation, route reduction, and transmission duration modeling

Feature Set Verified

IP Range to Minimal CIDR Blocks

Converts arbitrary start and end IPv4 address boundaries into the exact mathematical minimum set of aggregated CIDR prefix blocks, minimizing routing table bloat.

Data Volume Transfer Estimator

Computes transfer duration for backups, disk images, and database replication across link speeds from 10 Mbps up to 100 Gbps transit carrier feeds.

Realistic TCP/IP Overhead Modeling

Factors in a realistic 5% TCP protocol, framing, and encapsulation overhead factor to provide pragmatic estimates rather than theoretical maximums.

Instant Summarization Copy

Provides convenient clipboard copy buttons for calculated CIDR block lists and transfer calculation summaries for runbooks and change tickets.