Reseller Inventory and Profit Spreadsheet: Track Every Flip From Sourcing to Payout

You have forty things listed across eBay, Poshmark and Mercari right now. Something sold this morning for $58. You know roughly what you paid for it — maybe $7, maybe $9, it was a Saturday in April and there were six other things in the bag — and you have no idea what actually landed in your account after fees and the label.

That’s the whole problem with reselling. The individual flips feel obviously profitable. The bank balance disagrees, and you can’t tell which of the two is lying because nothing is written down in a form that subtracts.

Full walkthrough of the template used in this guide.

This is what to write down, how to do the subtraction, and what four numbers to read once you have three months of it.

The Only Equation That Matters

Sale price − platform fee − payment processing − shipping you paid − item cost = net profit

Five subtractions. Most resellers run two of them — sale price minus item cost — and that overstates the profit by roughly the fee load, which on the major resale platforms runs 10 to 20 percent before postage.

Two of the five hide especially well:

Shipping you paid is not the shipping the buyer paid. When the buyer covers postage, that money arrives in your payout and then leaves for the label. It nets to roughly zero, and it is not profit. When you offer free shipping, it comes straight out of your margin.

The item cost is easy on a $7 thrift find with a receipt and nearly impossible on a $40 estate-sale box lot of eleven items. Split the box cost across the items when you log them, at the moment you unpack, not eight months later at tax time when you’re guessing.

A Flip Worked End to End

Every number here is a stated assumption. Fee rates change and vary by category, so check your platform’s current fee schedule before copying the percentages — the structure is what transfers.

The item: a wool coat, bought at a Goodwill in March for $6.99, listed on eBay at $58, sold in June for $58 with the buyer paying $8.90 shipping.

Two things in that table catch people out.

First, the fee is charged on the total the buyer paid — item price plus buyer-paid shipping plus sales tax — not on the item price alone. Charging the buyer for postage doesn’t get you out of the fee on it. (eBay’s selling fees page sets out the current rate and the fee base: most categories run 13.6% plus a per-order fee of $0.30 on orders of $10 or less and $0.40 above that, with some categories materially higher or lower.)

Second, the flip is a 594% return on a $6.99 cost and it is also $41.51. Both facts matter and they matter differently, which is the point of the four numbers further down. (If eBay is your main channel, the fee side is worked through at three different sale shapes here.)

Now run the same coat somewhere else, so you can see what platform choice is worth:

Same coat, same price, a $4.91 spread. That’s small on one item and it is not small across 200. It’s also the wrong number to optimize on its own — see the sell-through section. The full platform-by-platform version of this comparison is worked out here.

The Columns You Actually Need

Copy this. Two sheets, not one — inventory and sales are different events, and jamming them into one row is why most reseller spreadsheets get abandoned in month three.

Sheet 1 — Inventory Log (one row per item, filled in the day you buy it)

Sheet 2 — Sales Tracker (one row per sale)

A fee lookup beats a typed percentage. In a spreadsheet that’s a nested IF or a small lookup table:

=IF(platform="eBay", 0.136,
 IF(platform="Poshmark", 0.20,
 IF(platform="Mercari", 0.10,
 IF(platform="Facebook Marketplace", 0, 0))))

Keep the rates in one place you can edit in thirty seconds, because platforms change them. A rate buried inside 200 copies of a formula is a rate you will never update.

The Four Numbers to Read

Once the log has a few months in it, four numbers answer nearly every decision a reseller makes. Everything else is decoration.

1. Net profit per item, by category

Not total revenue. Total revenue rewards volume, and volume in reselling mostly means more trips to the post office. Sort your sales by category and average the net profit. Most people find one or two categories carry the business and one category is a hobby they’ve been subsidising.

2. Sell-through rate, by platform

Items sold ÷ items listed, per platform. This is the number that stops you from chasing the lowest fee. A platform that takes 20% and moves 60% of your listings pays you more than one that takes 10% and moves 15%, because inventory that doesn’t sell has a return of exactly zero however low the fee is.

Run it with real numbers: 50 items listed at an average $40 sale price. At a 20% fee and a 60% sell-through, 30 items sell and gross profit after commission is 30 × $32 = $960. At a 10% fee and a 15% sell-through, 7.5 items sell and it’s 7.5 × $36 = $270. The cheaper platform loses by a factor of three.

3. Aged inventory

Count what’s been listed 30, 60 and 90+ days, and total what you paid for the 90+ bucket. That last figure is cash you converted into a pile in a spare room. It’s the most useful uncomfortable number in reselling, because it’s the one that tells you to reprice or clear out instead of sourcing more this weekend.

4. ROI per sourcing location

Total spent at a location versus revenue eventually realised from what you bought there. Most resellers have a favourite store that is sentimental rather than profitable, and one they visit rarely that quietly returns 4x. You cannot tell which is which from memory. What to actually look for on a sourcing run changes once you know your own numbers.

The Break-Even Price, Before You List

The most useful single formula in reselling is the minimum you can list something for and not lose money:

break-even price = (cost + shipping) ÷ (1 − fee rate)

The division matters. Fees are charged on the final sale price, so you can’t just add them to your cost — you have to gross up.

A $12 item you’ll ship for $5 on a platform taking 13.6%:

($12 + $5) ÷ (1 − 0.136) = $17 ÷ 0.864 = $19.68

Below $19.68 you are paying for the privilege of shipping a stranger a thing. Anything you want to earn sits on top: a 50% margin on cost means listing around $25.50, not $18.

Work this out before you list, and again before you accept an offer. It’s the number that turns “eh, I’ll take $18” into “no.”

Five Mistakes That Cost Real Money

Counting buyer-paid shipping as revenue. It arrives in your payout and leaves for the label. Log it in both directions or not at all — never just the inbound half.

Logging cost as the box price. A $40 lot of eleven items is not eleven $40 items and it is not eleven free items. Split it when you unpack.

Recording the payout instead of the sale. Platform payouts net out fees, refunds and sometimes several sales at once. Log the sale line by line and let the spreadsheet do the netting; otherwise your Schedule C gross receipts will be wrong, because the IRS wants gross sales with fees claimed as an expense, not a net figure.

Ignoring the aging column. Every unsold item is a small negative return compounding quietly. Ninety days is a decision point, not a status.

Tracking only what sold. Your sell-through rate and your sourcing ROI both need the misses in the data. A spreadsheet that only contains wins can’t tell you anything about where the money is going. That’s also where most reseller tax deductions get lost — the unsold, the mileage, the supplies.

Set It Up This Week

• [ ] Two sheets: Inventory Log and Sales Tracker, with the columns above
• [ ] A fee table in one place, with today’s rate for each platform you sell on
• [ ] Box lots split across items at the moment you unpack
• [ ] Buyer-paid shipping recorded in and out, or excluded from both sides
• [ ] A days-listed formula and a 90-day review on the calendar
• [ ] A break-even calculation you run before every listing
• [ ] Net profit averaged by category once you have 30 sales
• [ ] Sell-through by platform once you have 50 listings

Two months of honest entry will tell you more about your business than two years of feeling like the flips are going well.

If you’d rather not build all that from scratch, we sell it done.

Featured on ReadySheetGo

Reseller / Flipping Inventory & Profit Tracker — 9 tabs and 1,900+ auto-calculating formulas that run exactly this system. An Inventory Log for 200 items with category, source type, cost, platform and status; a Sales Tracker that applies a per-platform fee rate and returns net profit and ROI on every single item; a Platform Dashboard comparing revenue, fees, profit and sell-through rate side by side across eBay, Poshmark, Mercari, Facebook Marketplace, Depop, Etsy and Amazon; a 12-month P&L; an ROI tab with the break-even price calculator; an Inventory Aging report flagging items at 30, 60 and 90 days; a Sourcing Trip Log with spend and ROI by location; and a Schedule C tax summary with a mileage log. Colour-coded inputs, dropdown validation, sample data pre-filled. Works in Excel and Google Sheets, no macros. Instant digital download — $17.99.