Profit Calculator — Net Profit, Margin & ROI Per Sale
Enter your sale price, platform fee, item cost, shipping, and advertising. Instantly see net profit, margin %, and ROI for any marketplace or direct sale. Works for eBay, Etsy, Amazon, Poshmark, Mercari — or any channel.
Default uses an Etsy-style 6.5% fee. Change the rate to match your channel — 0% for direct, 13.35% for eBay, 15% for Amazon, 20% for Poshmark above $15, 10% for Mercari.
How it works
What the profit calculator measures
Revenue
Total amount the buyer pays: sale price + any shipping you charge. Net profit is calculated after every cost is subtracted from this number.
Platform fee
Enter the rate (%) and any flat per-order fee your marketplace charges. eBay: 13.35% + $0.40. Etsy: ~9.5% effective. Amazon: 15% referral. Poshmark: 20%. Mercari: 10%.
COGS
Item cost — what you paid the supplier, manufacturer, or thrift source. The single largest cost for most sellers and the most important input for ROI.
Ad + misc
Advertising spend plus a catch-all for returns, storage, prep, and any other variable cost you want to model per unit.
RELATED TOOLS
Pair the profit calculator with these.
Reverse-solve the minimum sale price that hits your target margin. Use it together with this calculator.
OPEN → AMAZONAmazon-specific referral + FBA + advertising math. Copy totals here for a cross-channel comparison.
OPEN → COMPAREEnter one price and see every platform's fees side-by-side instantly.
OPEN →How to calculate net profit, margin and ROI on any marketplace sale (2026)
The profit calculator above is platform-agnostic — it works for eBay, Etsy, Amazon, Poshmark, Mercari, Walmart, or any direct sales channel. Enter your sale price, fee rate, COGS, shipping, and advertising, and it shows you net profit, margin %, ROI %, and the full cost breakdown in real time as you type.
Margin vs ROI — which should you track?
Margin tells you what fraction of each sale is profit. ROI tells you how much profit you earn per dollar you invested. Use margin to decide whether a price point is sustainable. Use ROI to decide whether a product is worth sourcing at all. Both numbers are needed before you scale any SKU.
What fee rate should I enter for each platform?
eBay US: 13.35% + $0.40 flat. Etsy US: 6.5% transaction + 3% + $0.25 processing + $0.20 listing (enter ~9.5% effective or split across the rate and flat fee fields). Amazon: 15% referral (add FBA cost in the miscellaneous field). Poshmark: 20% above $15. Mercari: 10% flat. The platform-specific calculators (eBay, Etsy, Amazon, Poshmark, Mercari) pre-load the exact fee schedules automatically.
Per-unit vs per-month profit
This calculator is per-unit. Multiply by your expected monthly volume to get monthly profit, but not all costs are per-unit — rent, software, and your own time are monthly fixed costs that per-unit math doesn't capture. Per-unit math tells you whether the economics of a single sale work. Monthly P&L tells you whether the business works. You need both.
FAQ
Profit calculator questions answered
How do I calculate profit on a marketplace sale?
Net profit = Revenue (sale price + shipping charged) − platform fees − item cost − shipping cost − advertising − miscellaneous costs. Divide by revenue for margin %, divide by item cost for ROI %. The calculator above does all of this as you type.
What is a good profit margin for online sellers in 2026?
15–25% net margin is typical for established online sellers. New sellers often run 5–10% while building volume. Below 5% leaves almost no buffer for returns, fee changes, or shipping increases.
What is ROI and how is it different from profit margin?
ROI measures profit against what you invested (COGS + ads + misc). Margin measures profit against revenue. A 50% ROI means every $1 invested returned $1.50 in profit. Use ROI to decide if a product is worth sourcing; use margin to decide if your price is sustainable.
What platform fee rate should I enter?
Enter the all-in effective rate for your channel. eBay US: 13.35% + $0.40 flat. Etsy US: ~9.5% effective all-in. Amazon: 15% referral (add FBA in the misc field). Poshmark: 20%. Mercari: 10%. For direct sales with no platform: 0%.
Should shipping charged to the buyer count as revenue?
Yes — the buyer paid it, so it goes in your pocket (less any platform fees that apply to it). The calculator adds it to the sale price to form total revenue, then subtracts your own shipping cost to show the net contribution from shipping.
What's the difference between this and the platform calculators?
The platform calculators (eBay, Etsy, Amazon, Poshmark, etc.) use the marketplace's published fee schedule. This profit calculator is platform-agnostic — enter any fee rate for any channel. Use it when comparing channels or calculating profit for off-platform or direct sales.