The Reseller Profit Calculator Pack (eBay, Poshmark, Mercari): Eight linked calculators, every formula checked by recalculation

Eight calculators for reselling on eBay, Poshmark and Mercari. Sheets 1 to 3 give the profit on one sale after each platform's fees, shipping, packaging and what you paid: a $48 coat bought for $9 leaves $26.31 on eBay, $28.15 on Poshmark and $24.15 on Mercari in the worked example. Sheet 4 finds the price each platform needs for a target profit, sheet 5 sets the three side by side, sheet 6 gives the highest price you can pay for an item and still keep your profit and margin, sheet 7 shows what an offer or discount costs, and sheet 8 tracks sell-through and how long cash sits in stock. Fee rates were copied from each platform's own fee page on 19 October 2026 and sit in cells you can overwrite when they change; the eBay promoted listing ad rate is your own input. Not affiliated with or endorsed by eBay, Poshmark or Mercari. These are estimates, not tax advice. Every formula was recalculated and checked against an independent implementation before this shipped.

What is in it

8 calculators, one per sheet. Overwrite the blue cells with your own numbers and everything else follows. Nothing is locked, there are no macros, and it opens in Excel, Numbers, LibreOffice and Google Sheets.

• eBay profit per sale: What does an eBay sale leave after fees, shipping and cost?
• Poshmark profit per sale: What does a Poshmark sale leave after the fee and cost?
• Mercari profit per sale: What does a Mercari sale leave after the fee and cost?
• Price for a target profit: What must you list at on each platform to clear your profit?
• Platform comparison: Which platform leaves you more on this item at this price?
• Highest price to pay: What is the highest price you can pay and still hit your target?
• Offers and discounts: What does accepting an offer or a discount really cost you?
• Monthly sell-through: How fast is stock selling, and how long is cash tied up in it?

Every formula was checked

This pack contains 74 formulas. Before it was published, every one of them was recalculated by a spreadsheet engine and compared against an independent implementation of the same arithmetic written in Python. All 74 agreed to within a cent, and the workbook carries a Verification sheet saying so.

That is an unusual thing to be able to claim about a spreadsheet, and it is the main reason to buy this one rather than download a free template. A formula that looks right and is wrong is worse than no formula at all, because you will act on it.

What each calculator assumes

There is a sheet listing this, because a calculator that hides its assumptions is just a number generator:

• eBay fees use the general category row (13.6% up to $7,500 an item) and the per-order fee from eBay's fee page, 19 October 2026; sales above $7,500 and categories with their own rate need the rate cells changed. The fee and the ad rate are charged on the total including shipping and sales tax, as eBay describes. One item per order.
• Poshmark's fee is a flat $2.95 under $15 and 20% at $15 or more, from Poshmark's support page, 19 October 2026. The fee is taken on the sale price. Shipping is 0 because in the example the buyer pays the label; enter any shipping discount you fund.
• Mercari's 10% selling fee applies to the item price plus buyer-paid shipping, with no separate payment processing fee, for listings created or updated from 6 January 2025; from Mercari's help center, 19 October 2026. Instant Pay is $3 a cash-out and direct deposit is free.
• Each price is the exact break-even for your target, before rounding to a listing price. eBay assumes the order total is over $10, and the check line says so if it is not. Ad and fee rates are the same as sheets 1 to 3.
• The item sells at the same price on each platform, which it may not: this compares fees and shipping, not demand. The buyer's total differs by platform because of shipping and buyer fees. Fee rates are the ones on sheets 1 to 3.
• The expected sale price is your own estimate, best taken from items you have sold. It ignores the time the item sits unsold; sheet 8 measures that. Fees are entered for that one sale price.
• The fee is a share of the price plus any fixed fee, which fits Poshmark at $15 or more and Mercari; for eBay, run both prices through sheet 1. A percent-off sale works the same way: enter the discounted price as the offer.
• Items sell in the order they came in and at this month's pace. Averages hide slow items: a few old pieces can hold more cash than the average suggests. Profit counts the cost of what sold, not what you bought this month.

What this is not

Not financial, tax or legal advice, and not a recommendation to buy, sell, borrow or sign anything. These are calculators: they show what a choice costs, not which choice is right for you. Where a published rate or threshold is used it is the one current when the pack was built; those change, the arithmetic does not.

Honest about the format

One .xlsx workbook, 8 calculator sheets plus Start Here, Assumptions and Verification. Not a PDF, not a physical product, not a Notion template. Available immediately after purchase; nothing ships.

Refunds

If this isn't what you expected, email me within 30 days and I'll refund you in full. No need to explain. Because it's an instant download I can't take the file back, so I'd rather you just had your money back.