Reselling ROI Calculator

How to use the reselling ROI calculator

There is no shipping field, so take postage you pay off the payout before you type it. If you only know the sale price, the "You receive" line of the marketplace fee calculator gives you the payout.

The form opens with example values (40 purchase cost, 5 extras, 78 payout, 21 days): profit 33, ROI 73.3%, ROI per 30 days held 104.8%.

The ROI formula for resellers

The calculator runs exactly this:

Extras count as money invested here. The resale profit calculator takes a different view: its "ROI on cost" subtracts extras from profit but divides by purchase cost alone. Run the jacket example below through both and you get 104.7% here and roughly 118% there. Neither is wrong, but mixing them is.

Decision rule: before you compare ROI figures from two tools or two spreadsheets, check what each divides by.

Adding holding time: annualised ROI

The per-30-days result is a simple rate. It spreads ROI evenly across the days and does not compound. To annualise it the same way, multiply ROI by 365 and divide by the days held.

Take the jacket from the next section: 104.7% ROI over 60 days is 52.3% per 30 days, or 636.7% annualised. That assumes every payout goes straight into an equally good deal, all year, so use it to rank deals, not to predict a year.

• If two deals have similar ROI, the one that pays out sooner wins.
• If one deal is much slower, its days are the shakiest input. Rerun it with double the days before you commit: the jacket at 120 days drops to 26.2% per 30 days.

ROI vs margin in one example

Same flip, two percentages. ROI tells you what each złoty you spent brought back; margin tells you what share of the sale price you kept. Use ROI to decide what to buy and margin to set prices and markdowns. ROI vs margin vs markup sets out all three.

Comparing two deals

Now a second example deal. You buy trainers for 170 zł with 5 zł of extras and sell them for 250 zł on Allegro Lokalnie at the same 7.9%. The payout is 230.25 zł, 14 days after you bought them. Profit is 55.25 zł and ROI 31.6%.

The jacket wins on ROI and on cash, 94.20 zł against 55.25 zł. The trainers win once time counts: the money is free for the next buy after two weeks instead of two months.

• If you find more good deals than you can afford, rank by ROI per 30 days. Cash that comes back sooner buys the next item sooner.
• If deals are scarce and cash is not, rank by profit in money. Two trainer flips out-earn one jacket, but only if you find the second pair.
• Before you buy, turn your floors into a walk-away price with the maximum buy price calculator. Its ROI floor divides by the buy price alone, so type its answer back in here to see your ROI with extras counted. Example: the jacket's 200 zł sale, 10 zł extras and a 100% ROI floor give 87.10 zł there, which is 89.7% ROI here.

Limits of ROI as a decision metric

• Tiny costs inflate ROI. Example: a 5 zł item that leaves 20 zł profit is a 400% ROI and still only 20 zł. Keep a profit floor in money next to any ROI floor.
• The payout is a forecast. Every result inherits the error in the price you expect. The break-even price calculator shows the lowest price at which the deal still breaks even.
• Time and overheads are missing. Hours, subscriptions and bulk packaging belong in the monthly P&L of the resale profit guide.
• Unsold stock is invisible. Per-deal ROI only exists for items that paid out. In a monthly review, add the cost of unsold items to total investment.
• Refunds and tax. Allegro refunds the Lokalnie fee if you refund the buyer through Allegro; your costs and time are not refunded. Results are before income tax. This is not tax advice; ask a tax adviser.