Discount Impact on Margin

How to use it

Enter your price, your unit cost and how much you are thinking of discounting. The calculator works out what the discount does to gross profit per unit, and how much additional volume you would need to end up exactly where you started.

Where the number comes from

• Gross profit per unit is price minus unit cost. A discount comes entirely out of that figure, because the cost does not move.
• The volume needed is total gross profit before the discount divided by gross profit per unit after it.
• The uplift required is that figure expressed as a percentage increase on current volume.
• The relationship is not proportional. Discounting a low-margin product requires far more extra volume than discounting a high-margin one, because the discount consumes a larger share of the profit.
• Where the discounted price falls below unit cost, no volume solves it and the calculator says so rather than returning a number.

What goes wrong

The part most calculators leave out.

• This measures gross profit only. Serving more customers usually adds support, delivery and account management costs, so the real volume needed is higher than shown.
• It assumes the discount wins genuinely incremental business. In practice a large share goes to customers who would have paid full price, and for those the volume uplift is zero and the loss is immediate.
• Discounts anchor expectations. A customer who bought at 15% off rarely returns to list price, so a one-off promotion often becomes a permanent price cut with none of the volume.
• Competitors respond. If a discount works, it gets matched, and the market ends up at the lower price with the same shares.
• The arithmetic says nothing about strategy. Buying market share below margin can be rational when there are switching costs or network effects — but that is a deliberate investment, not a pricing decision.

Questions

Why does a small discount need so much extra volume?

Because the discount comes entirely out of gross profit, not out of revenue. If your margin is 40%, a 10% price cut removes a quarter of your profit per unit — so you need a third more volume to replace it.

Is it better to discount or to add value?

Adding something that costs you less than the discount is nearly always better arithmetic, because it protects the price. A 15% discount on a 500 product gives away 75 of pure profit; a bonus that costs you 30 is worth more to the customer and less to you.

What about volume discounts on large orders?

They can be sound where the larger order genuinely lowers your cost — fewer shipments, less handling, better production runs. The test is whether unit cost actually falls, not whether the order feels big.

Does anything I type get sent anywhere?

No. The whole calculation runs in your browser. Nothing is transmitted, stored, or logged, and there is no account to create.