# eBay & Mercari 90-Day Sold Comp, IQR & 13.25%-Fee Net Flip Margin Calculator

> **Canonical Interactive Calculator**: `https://ceadigital.io/tools/ebay-category-margin-calculator`
> **LLM Markdown Mirror**: `https://ceadigital.io/tools/ebay-category-margin-calculator.md`
> **1-Row Free Live Sold-Comp Lookup**: `POST https://ceadigital.io/v1/tools/free-preview` with `{"tool": "sold-comps", "query": "Fujifilm X100V Silver Digital Camera", "secondary": "used"}`

## Formula Reference: Realized Sold Median, IQR Spread & Net Flip Profit

1. **Interquartile Range (IQR) Outlier Rejection**:
   - $\text{IQR} = Q_3 (75\text{th percentile}) - Q_1 (25\text{th percentile})$
   - Filters out "replacement box only", broken for-parts listings, and accessory spam before computing the **90-Day Realized Sold Median** (including Accepted Best Offers).
2. **Platform Fee Schedules**:
   - **eBay Most Categories**: `13.25%` of total sale price + `$0.30` per order
   - **Mercari**: `10.00%` flat seller commission
   - **Poshmark**: `20.00%` flat commission on sales `$15+`
3. **Net Flip Profit & ROI**:
   $$\text{Net Profit} = \text{Median Sold Price} - \text{Target Buy Price} - \text{Platform Fee} - \text{Shipping Buffer}$$
   $$\text{Net ROI (\%)} = \left(\frac{\text{Net Profit}}{\text{Target Buy Price}}\right) \times 100$$

## Honest Price-Per-1,000 Comparison vs. `caffein.dev/ebay-sold-listings`

| Metric | `ceadigital/ebay-sold-listings-comps-scraper` (`ebay-mercari-sold-comps-api`) | `caffein.dev/ebay-sold-listings` |
| --- | --- | --- |
| **Price per 1,000 Comps** | **`$2.50 / 1,000`** (Apify Bronze+) or **`$29/mo`** Direct Key (`5,000` hits) | `$4.00 / 1,000` + start fee |
| **Accepted Best Offer Realized Price** | **Yes** | Strikethrough list price only |
| **IQR Spread (`Q3 - Q1`) & Accessory Spam Filter** | **Yes (`filterDealers: true`)** | No |
| **Built-In eBay (13.25%), Mercari (10%) & Poshmark (20%) Net Profit Math** | **Yes** | No |
| **Real-Time Telegram / Webhook Deal Sniper (`monitorMode: true`)** | **Yes** | No |