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How big a discount can you give before you lose money?
A simple rule for sales events like Black Friday: know the largest safe discount per product.
Last reviewed 2026-11-11
A discount comes out of profit, not out of revenue in general. If your margin is 25%, a 25% discount means you earn nothing on that sale, and a bigger discount means a loss.
The largest safe discount depends on the margin of each product. Items with thin margins cannot take a sale. Items with high margins can.
- Work out the margin of each product at its normal price.
- Choose a discount for the event and check which products would sell below cost.
- Leave those out of the sale, or discount them less.
The discount simulator in the calculator shows the largest safe discount and how many extra units you would need to sell to earn the same profit.