Reselling profit vs ROI: they answer different questions.

What is resale profit?

At its simplest, profit is what remains after subtracting the costs attributable to the sale from the revenue received.

The exact costs relevant to you depend on the transaction. They might include marketplace charges, postage you absorb, packaging, cleaning or repairs. Use current actual costs rather than assuming every platform or sale works the same way.

What is ROI?

Return on investment expresses a return relative to the amount invested. A simple item-level resale calculation can compare profit with the purchase cost:

Why profit and ROI can point in different directions

Selling speed changes the picture

Money tied up in stock cannot simultaneously fund another purchase. An item with a strong theoretical return that sits unsold for months may be less attractive than a lower-margin item that sells reliably and quickly.

This is why stock turn matters. ROI without time can make slow-moving inventory look better than it feels in a real resale business.

Effort matters too

Two £20 profits are not necessarily equivalent if one requires extensive cleaning, testing, research, photography, packing or buyer communication and the other is straightforward.

You do not have to assign a formal hourly rate to every item, but you should recognise effort as a real constraint when comparing opportunities.

Risk belongs in the decision

Consider how confident you are in the item's identity, condition, market evidence and likely costs. A high projected ROI based on weak evidence may be less attractive than a lower projected return supported by strong comparisons.

So what should a reseller measure?

For individual items, a useful minimum set is:

• purchase cost;
• sale revenue;
• direct costs;
• actual cash profit;
• ROI using a clearly defined calculation;
• time to sell.

At a broader level, also look for patterns: categories that repeatedly perform well, stock that stays unsold, sourcing channels that produce stronger results and how much capital is sitting in inventory.

Before buying: use ranges, not false precision

Before an item has sold, profit and ROI are estimates. If the resale value itself is uncertain, calculate against a realistic range rather than treating one optimistic asking price as guaranteed revenue.

Our Is It Worth Reselling? guide explains the full pre-purchase decision, while How Much Profit Should You Make Reselling? looks at why there is no universal “correct” margin.