# Network & Subnet CIDR Studio

> Private IPv4 & IPv6 Subnet CIDR Calculator | Privatools
> Canonical URL: [https://privatools.dev/tools/subnet-calculator/](https://privatools.dev/tools/subnet-calculator/)
> Markdown Alternate: [https://privatools.dev/tools/subnet-calculator.md](https://privatools.dev/tools/subnet-calculator.md)
> Execution Architecture: 100% Client-Side In-Memory Execution (Zero Remote Egress)

## Overview
Calculate subnet masks, CIDR notations, IP address ranges, broadcast addresses, and wildcard masks for IPv4 and IPv6. Design subnets with visual bitmask allocations, hierarchy trees, and overlap detection.

## Format Specifications
- **Category:** Security & Dev
- **Supported Formats:** `IPv4`, `IPv6`, `CIDR`, `VLSM`, `Binary`, `Hex`
- **Privacy Guarantee:** 0 bytes uploaded to remote servers. All computation executes locally in browser memory.
- **Compliance:** GDPR, HIPAA & SOC 2 Friendly (process sensitive payloads and PII directly on your local device).

## Technology Stack
- BigInt 128-bit IPv6 Math
- 32-bit Bitwise Engine
- Visual CIDR Allocation Matrix
- RFC 1918 Private Range Validator

## How It Works
1. IP addresses and prefixes are parsed into 32-bit integers (IPv4) or 128-bit BigInts (IPv6).
2. Bitwise arithmetic derives network IDs, broadcast addresses, usable host spans, and wildcard masks instantly.
3. Hierarchical subnet splitters partition address blocks into balanced /24, /25, /26, or custom prefix sizes.
4. Overlap detectors check prospective subnets against existing enterprise VPC routing tables.

## Practical Use Cases
### Cloud VPC & Infrastructure Architecture
Plan non-overlapping subnets across AWS VPCs, GCP Virtual Private Clouds, and Azure VNets for secure hybrid networking.

### Enterprise Network Engineering
Carve office LANs, guest Wi-Fi networks, and server VLANs out of corporate RFC 1918 private IP blocks.

### Firewall & Security Rule Configuration
Calculate exact CIDR blocks and wildcard masks for Cisco, Juniper, pfSense, and iptables access control lists (ACL).

### IPv6 Migration Planning
Explore 128-bit IPv6 /64 and /48 address allocations and zero-compression notation without manual hexadecimal math.

## Frequently Asked Questions
### Does this subnet calculator send internal network IP data over the internet?
No. All IP calculations are performed locally in your browser using pure JavaScript bitwise arithmetic. Your internal network topologies remain 100% private.

### Does it support both IPv4 and IPv6?
Yes. It features dedicated calculation engines for traditional 32-bit IPv4 networks and 128-bit IPv6 allocations.

### Can it detect overlapping subnets?
Yes. The built-in collision detector compares two subnets and alerts you if there is an address collision, subset inclusion, or superset conflict.

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- [Provably Fair & Random Studio](https://privatools.dev/tools/random-studio/)

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