# PRD - Gridfinity Calculator

## 1. Overview
The Gridfinity Calculator is a web tool designed to help makers plan their Gridfinity layouts. It calculates the number of baseplates that fit in a specific container and the maximum bin height allowed.

## 2. Target Audience
- 3D printing enthusiasts using the Gridfinity system.
- Workshop organizers and hobbyists.

## 3. Key Features
- **Dimension Input:** Width, Length (Depth), and Height of the target drawer/container.
- **Unit Toggle:** Support for Inches (decimal/fractional) and Millimeters.
- **Spec Overrides:** Modify standard 42mm grid and 7mm height unit.
- **Dynamic Results:**
  - Total full grid squares (e.g., "5x4 grids").
  - Fit percentage/fractional grids (e.g., "5.2 x 4.1 grids").
  - Vertical Unit Height (U) for bins (e.g., "6U").
  - Remaining space (gap) in mm/inches.

## 4. Technical Constraints
- Must be fast and lightweight.
- Must work offline once loaded (single-page build).
- Mobile-responsive design.

## 5. Calculation Logic
- `Grid Count = Floor(Drawer Dimension / Grid Spec)`
- `Exact Fit = Drawer Dimension / Grid Spec`
- `Bin Unit Height (U) = Floor((Drawer Height - Base Thickness) / Height Unit)`
- *Default Base Thickness:* 4.8mm
- *Default Grid Spec:* 42mm
- *Default Height Unit:* 7mm