# Data Quality Report

## Brand Size Matcher — Measurement Data

**Last Updated:** 2026-02-12
**Version:** 1.0.0

## Sourcing Methodology

All garment measurements in this project are **approximations** derived from Claude's knowledge of publicly available brand size charts, fitting guides, and retail documentation. They represent typical garment measurements (not body measurements) for men's clothing.

### Data Sources
- Brand official websites and size guides
- Publicly available retail size charts
- General industry sizing standards and conventions

### What We Measure
All measurements are in **centimeters (cm)** and represent **garment measurements** (the actual dimensions of the clothing item laid flat), not body measurements.

| Dimension | Description |
|-----------|-------------|
| Chest | Full circumference at chest level |
| Shoulder | Seam to seam across the back |
| Waist | Full circumference at natural waist |
| Sleeve | Shoulder seam to cuff (shirts) or shoulder drop (t-shirts) |
| Length | Back of collar to hem (shirts) or shoulder to hem (t-shirts) |
| Hips | Full circumference at hip level (jeans) |
| Inseam | Crotch to hem (jeans) |

### Range Format
Each measurement is stored as a min/max range (e.g., chest: 102-106 cm) to account for:
- Manufacturing tolerances (±1-2 cm)
- Style variations within a size (slim vs regular fit)
- Seasonal production differences

## Confidence Ratings

| Rating | Brands | Notes |
|--------|--------|-------|
| **High** | Zara, H&M, Uniqlo, Levi's, Gap, Nike, Adidas | Large international brands with well-documented, consistent size charts |
| **Medium** | Tommy Hilfiger, Ralph Lauren, COS, Mango, M&S, Jack & Jones | Reliable charts but more variation across product lines |
| **Medium** | Peter England, Allen Solly, Van Heusen, Louis Philippe | Indian brands using numeric sizing; well-established charts |
| **Medium-Low** | FabIndia | More relaxed fits with greater variation across styles |
| **Medium** | Snitch | Indian D2C brand; slim & oversized fits. [Size chart](https://www.snitch.co.in/pages/shirt-size-chart) |
| **Medium** | Bewakoof | Indian D2C brand; regular & oversized fits. [Size guide](https://www.bewakoof.com/size-guide) |
| **Medium** | The Souled Store | Indian D2C brand; regular & oversized fits. [Size guide](https://www.thesouledstore.com/size-guide) |
| **Medium** | Rare Rabbit | Indian premium D2C brand; slim fit. [Sizing help](https://www.thehouseofrare.com/pages/sizing-help) |
| **Medium** | Campus Sutra | Indian D2C brand; regular fit. [Size chart](https://www.campussutra.com/pages/size-chart) |

## Known Limitations

1. **Approximations, not exact measurements**: Data is derived from Claude's training knowledge, not from direct measurement of garments. Actual measurements may differ.

2. **Fit variations**: Most brands offer multiple fits (slim, regular, relaxed) within the same size. Our data represents a typical/regular fit unless otherwise noted.

3. **Regional differences**: Some brands size differently across regions (e.g., Asian fit vs European fit). Data represents the most common/global sizing.

4. **Temporal drift**: Brands occasionally update their sizing. This data represents a snapshot and may become outdated.

5. **Category coverage**: Not all brands offer all categories. Coverage is based on each brand's primary product lines.

6. **Gender**: Current data covers **men's sizing only**. Women's and unisex sizing may be added in future versions.

## Matching Algorithm

The matching engine uses an **Intersection over Union (IoU)** approach:

1. For each measurement dimension, calculate the overlap between the source size range and each candidate size range
2. IoU = overlap_length / union_length (0 to 1)
3. Weighted aggregate across dimensions:
   - **Shirts/T-shirts**: Chest 35%, Shoulder 25%, Waist 20%, Sleeve 10%, Length 10%
   - **Jeans**: Waist 45%, Hips 30%, Inseam 25%
4. Missing dimensions are skipped, weights redistributed proportionally

### Match Quality Labels
- **Excellent** (≥90%): Very close dimensional match
- **Good** (≥75%): Minor differences, likely comfortable
- **Approximate** (≥60%): Noticeable differences, try before buying
- **Loose Match** (<60%): Significant differences, exercise caution

## Contributing

See [contribute.html](../contribute.html) for instructions on submitting corrections or adding new brand data.

## Disclaimer

This tool is provided for informational purposes only. Always try on clothing before purchasing when possible, and refer to the specific brand's current size chart for the most accurate information. The creators of this tool are not responsible for sizing decisions made based on this data.