Many shops take pride in their “best-seller” — but the painful truth is that the item you sell the most can be the one losing you the most money. Here are 5 reasons a product can be popular but unprofitable, and how to catch it.
1. Priced too low, markup too thin
Best-sellers are often popular because they’re cheap — but if the margin per item is tiny, selling more just wears you out for nothing. Sell 100 units at ฿2 profit each = ฿200, while another item sells 20 units at ฿30 profit = ฿600. (See: How to price products for profit)
2. Costs went up, price stayed the same
Ingredient prices creep up quietly (oil, milk, flour), but you never raised your selling price. Your per-item profit shrinks every month without you noticing — and your best-seller takes the biggest hit because it sells the most.
3. Too many discounts and promos
“20% off” or “buy one get one” really does lift sales — but if your original margin was only 25%, a 20% cut leaves just 5%. You sell more but earn less overall.
4. Lots of hidden costs
Some items look cheap on ingredients but carry hidden costs: bags/packaging, waste/expiry, delivery-app fees. Small each time, but they eat real profit. (Read: Hidden costs that shrink your profit)
5. Watching sales, never per-item profit
The biggest reason is measuring the wrong thing — you track what sells most (units/revenue) but never what earns most. The item worth promoting is the one with high per-item profit, not just high volume.
How to check: look at per-item profit, not sales
Rank your products by per-item profit × units sold = total profit per product, and you’ll see clearly which ones make money and which you’re basically giving away.
A tool like Posless stores each product’s selling price + cost, so when you sell it tells you the per-item profit instantly, and you can snap receipts to update costs in LINE — showing which items to raise, which to stop discounting. (More on gross vs net: Gross profit vs net profit)
Frequently asked questions
Q: Should I drop products with tiny per-item profit? A: Not always. Some low-margin items are “loss leaders” that bring customers in to buy your higher-margin products. Look at the whole picture before cutting.
Q: I’m afraid to raise prices and lose customers — what should I do? A: Raise gradually, or only on items whose costs truly jumped, and add value (packaging/service) so customers still feel it’s worth it.
Q: How do I know real per-item profit if I don’t record every sale? A: Use a tool that logs each sale and stores cost against the product, so profit is calculated automatically — no mental math.
Summary: Popular ≠ profitable. A best-seller can lose money through low prices, rising costs, frequent promos, hidden costs, and measuring sales instead of profit. The fix is to focus on per-item profit and promote the items that actually earn.