How to Use This Flipping Calculator
Retail and online arbitrage is a numbers game. The sellers who make money consistently do one thing differently: they run the math before they buy, not after.
- Buy price is what an item costs you to source (including any sales tax and sourcing fees).
- Resale price is the realistic price your item will fetch on eBay, Amazon, Poshmark, Mercari, or Depop — check sold listings, not asking prices.
- Platform fee rate + fixed fee are the marketplace's cut. eBay ~13.25% + $0.30, Poshmark 20% ($2.95 under $15), Mercari ~10% + payment, Depop 10%.
- Shipping is what comes out of your pocket for "free shipping" offers.
- Days to sell estimates how long your money is tied up. Money sitting on a shelf is money you can't flip again.
Reading Your Opportunity Score
The 0–100 score weighs net margin, ROI, and how quickly the item will sell. 70+ = strong flip, take it if the demand is real. 40–69 = only if it sells fast or you already have the item. Below 40 = skip unless it's a guaranteed fast mover you're sourcing to clear. A good rule of thumb for scaling: only buy inventory that clears 100% ROI and sells within 30 days.