ROI (return on investment) is the single most useful metric for sourcing decisions. It tells you how much profit your dollars generate — which is what actually matters when deciding whether a $15 thrift find is worth buying.
ROI vs margin: what's the difference?
They sound similar but measure different things:
- Margin = net profit ÷ sale price. “What percentage of each sale do I keep?”
- ROI = net profit ÷ cost of goods + shipping cost. “How much profit did each dollar I spent generate?”
For a $100 sale that cost you $20 to source and ship and netted $50: margin is 50%, ROI is 250%. Both metrics are correct — they answer different questions.
The ROI formula
ROI % = (net profit ÷ total cost) × 100
net profit = sale price − all eBay fees − COGS − shipping cost − packaging
total cost = COGS + shipping cost + packaging
Worked example
You buy a pair of sneakers at $60, sell them for $160 with $10 shipping charged (so $170 total transaction), pay $10 to ship, and use $1 in packaging. On eBay.com, athletic shoes that sell for $150 or more pay 8.0% and no per-order fee (below $150 they pay the standard 13.6% + per-order fee):
- Sale total: $170
- FVF (8.0% of $170): $13.60
- Per-order fee: $0.00 (waived on sneakers $150+)
- Total eBay fees: $13.60
- COGS + ship cost + packaging: $60 + $10 + $1 = $71
- Net profit: $170 − $13.60 − $71 = $85.40
- Margin: $85.40 / $170 = 50.2%
- ROI: $85.40 / $71 = 120.3%
Why ROI is the right metric for sourcing
Imagine two potential items at a thrift store:
- Item A: buy $5, sells $30 → net ~$18 → margin 60%, ROI 360%
- Item B: buy $80, sells $200 → net ~$80 → margin 40%, ROI 100%
Item B prints more dollars per sale, but Item A turns each dollar into $3.60 of profit. If your bottleneck is capital (you have limited cash to source with), Item A wins. If your bottleneck is time (sourcing one item takes the same effort as another), Item B wins because the dollar profit is larger.
Rule of thumb: capital-constrained resellers optimise for ROI. Time-constrained resellers (full-timers with no cash limit) optimise for absolute profit per sale.
ROI benchmarks for eBay flippers
| Sourcing channel | Typical ROI per item |
|---|---|
| Thrift stores / garage sales | 200–600% |
| Estate sales / auctions | 100–300% |
| Retail arbitrage (clearance) | 50–150% |
| Wholesale / liquidation pallets | 80–200% |
| Online arbitrage | 30–80% |
The eBay profit calculator shows ROI alongside margin for every scenario you model — flip between categories, store tiers and promoted rates to see the trade-offs in real time.
A simple sourcing rule using ROI
Set a minimum ROI threshold before you ever buy: for most part-timers, 100% ROI is a reasonable floor. That means every dollar in becomes at least two out, before factoring time. If you can't see a clear path to 100% ROI on an item, walk away.
Frequently asked questions
What is a good ROI on eBay?
For thrift sourcing, aim for 200%+ per flip. For retail arbitrage, 50%+. Anything under 50% needs very fast turnover or large average ticket to justify the cash and time tied up.
Should I use margin or ROI to evaluate a flip?
ROI when you're deciding whether to source the item (capital efficiency). Margin when you're deciding how to price it (per-sale profitability). Both metrics belong on every sourcing spreadsheet.
How do I improve ROI without changing what I sell?
Source cheaper (negotiate, buy bundles, hit estate sale Sundays), ship cheaper (eBay Standard Envelope for sub-$20 items, Pirate Ship consolidators), or move to lower-FVF categories like sneakers and guitars.