Calculate your ZFS pool’s usable & effective capacity with ease!
A lightweight, responsive web app to help you plan ZFS storage pools, compare redundancy levels, and estimate real-world usable space after ZFS overhead. Built with Tailwind CSS, Font Awesome, and vanilla JavaScript.

• 🎛️ Dynamic Inputs
  • Number of disks
  • Disk size (TB / GB toggle)
  • Redundancy level (None, RAIDZ1/2/3, Mirror)
• 📊 Instant Results
  • Usable Capacity (pre-overhead)
  • Effective Capacity (after redundancy & ZFS overhead)
  • Calculated ZFS Overhead (%)
  • Mirror pair count & fault-tolerance explanation
• ⚙️ Accurate Overhead Model
  • Partition labels, alignment, reserved partitions
  • VDEV labels, boot blocks, metaslab loss, slop space
• 🌐 Responsive & Accessible
  • Mobile-first layout
  • Keyboard-accessible controls & ARIA labels
• 🎨 Modern UI
  • Dark theme with TikTok-inspired gradient accents
  • Tailwind CSS utility classes
  • Font Awesome icons

1. Clone the repo

   git clone https://github.com/your-username/zfs-storage-calculator.git
   cd zfs-storage-calculator

2. Open index.html in your favorite browser

   open index.html

3. Start calculating!
   • Enter disk count & size
   • Select TB or GB
   • Choose your redundancy level
   • View results instantly

No build tools or servers required – just static HTML/CSS/JS!

1. Raw Capacity = number_of_disks × disk_size
2. ZFS Overhead
   • Partition & alignment labels
   • Reserved partitions & boot blocks
   • Metaslab allocation loss (0.5% estimate)
   • Slop space (1/32 of pool)
3. Usable Capacity (pre-overhead) = usable_disks × disk_size
4. Effective Capacity = (usable_capacity × (1 − total_overhead%))

All calculations assume 1 GB = 10⁹ bytes, 1 TB = 10¹² bytes.

1. Fork it (🔀 “Fork” button at the top right)
2. Create your feature branch:

   git checkout -b feature/my-awesome-calc

3. Commit your changes
4. Push to the branch
5. Open a Pull Request ✨

Please follow the existing code style and include descriptive commit messages.

Made with ❤️ by altan.me
Enjoy calculating! 🎉