FlippoWhat a flip actually made you
Sale price minus what you paid is the number most resellers carry in their head, and it is wrong almost every time. Not by a little either - on a low-margin flip it is the difference between a profit and a loss you did not notice.
The gap is made of small, boring things: the platform's cut, the postage you paid because the buyer got free shipping, the padded envelope, the petrol to the car boot sale. Each one is too small to remember and they are never too small to matter.
What actually comes off the top
Work down this list for every sale, and the number at the bottom is your profit.
| Line | Example | Amount |
|---|---|---|
| Sale price | What the buyer paid you | 600 |
| − Platform fee | Typically 5–13% depending on where you sold | 48 |
| − Payment fee | Often bundled into the platform fee, sometimes not | 12 |
| − Shipping you paid | Not what you charged - what left your account | 89 |
| − Packaging | Box, tape, bubble wrap, label | 15 |
| − What you paid for the item | Its share of the purchase, see below | 250 |
| = Profit | 186 |
The headline number was 350. The real one is 186. Nothing unusual happened in that example - it is an ordinary sale with ordinary costs.
ROI is measured against what you paid, not what you spent
This one causes more arguments than it should. There are two defensible denominators, and they answer different questions.
Profit ÷ purchase price answers how good was this buy? That is the decision you make standing in a charity shop with the item in your hand, and it is the only one you can act on before money changes hands. In the example above: 186 ÷ 250 = 74%.
Profit ÷ every cost including fees and postage answers how efficient was the whole operation? Useful at the end of the quarter, useless in the shop, because you do not yet know what it will cost to ship or what the platform will take.
Pick one and never mix them. A shop that quotes 74% on Monday and 43% on Tuesday for the same flip has not learned anything about the flip - it has learned that its own numbers cannot be trusted, and that is worse than not measuring at all.
The haul problem
Most sourcing is not one item at a time. You pay 1,000 for a box of forty things and then sell them one by one over the next six months. So what did any single item in that box cost?
There are three ways people do this, and only two of them are any good.
Split it evenly
1,000 ÷ 40 = 25 each. Fast, defensible, and fine when the contents are broadly similar - a box of DVDs, a bag of the same brand of jeans. It falls apart when one item is most of the value: a lot with a console and thirty loose cables says the console cost 25, which will make it look like the best flip of your life.
Split it by what each is worth
Estimate the resale value of everything, and give each item the same share of the cost as it has of the total value. The console taking 60% of the value carries 60% of the cost. More work, and much closer to the truth when the box is uneven. This is the right default for mixed lots.
Assign it all to the first thing that sells
Some resellers put the whole 1,000 against the first sale and treat everything afterwards as free. It is not wrong in a cash-flow sense - you are whole once the box has paid for itself - but it destroys per-item numbers. Every later flip shows an infinite return, so you can never tell which items are worth sourcing again. That is the one thing per-item tracking was for.
The number nobody tracks that predicts the most
Profit tells you about a sale that already happened. Days on hand tells you about the ones that have not.
An item with 200 profit that sat for eleven months made you less, per month of shelf space and per hour of attention, than one with 80 profit that moved in three weeks. Sourcing decisions get much better once you know which categories move and which quietly accumulate.
The related figure is sell-through: of everything you have listed, what fraction has sold. Low sell-through with high average profit usually means you are pricing above the market and being paid occasionally for your patience.
Why a spreadsheet stops coping
None of this is hard arithmetic. It is hard bookkeeping, which is different, and it is where spreadsheets give out:
- A haul is one purchase and many rows, and linking them by hand gets skipped.
- Five identical items need five rows so you can sell one, and copy-paste makes six by accident.
- Nobody opens a spreadsheet at a car boot sale on a Saturday morning.
- Formulas quietly break, and a broken formula still shows a number.
Most resellers start in Excel or Google Sheets and it works fine for a while. It stops working at the point where you have enough inventory for the answers to matter.
Flippo does this arithmetic for you
Record the purchase, add the items, log the sale. Profit, ROI, days on hand and sell-through are worked out per item, including fees and shipping - and a haul stays one purchase with many items attached to it.