Margin and pricing
Discount and markdown calculator
A discount takes a percentage off the price, but it comes entirely out of profit, because the cost of the item does not move. On a 25 percent margin, a 15 percent discount removes 60 percent of the profit on that sale.
Price before the discount
Percentage off the price
Your margin before discounting
The formula
- Original price
- The price before the discount. If your list price is already the product of routine discounting, use what customers actually pay rather than the number on the tag, or the calculation measures a reduction from a price nobody was charged.
- Discount
- The percentage coming off. Stacked offers do not add: twenty percent followed by a further ten is twenty-eight percent off, not thirty, because the second reduction applies to the already reduced price.
- Gross margin
- Your gross margin on the item before discounting. This is what turns a shopper calculator into a pricing decision. Leave it out and you get the sale price. Fill it in and you also get the margin left afterwards and the volume increase you would need just to hold the same gross profit.
A worked example
The outdoor gear brand sells a jacket at 250 against a 25 percent gross margin, so the jacket costs 187.50 and earns 62.50. A fifteen percent promotion drops the price to 212.50, and the intuition in the room is that this costs fifteen percent.
The cost of the jacket has not changed. Profit falls from 62.50 to 25, which is sixty percent of the profit gone. To finish the promotion with the same gross profit the brand would need to sell two and a half times the units, not fifteen percent more. The rule is worth memorising: divide the discount by the margin and that is the share of profit you are giving away.
Now run it as the quarter actually went. The brand normally sells 400 jackets for 100,000 of revenue and 25,000 of gross profit. The promotion works and volume rises fifty percent to 600 units, which is a strong result by any campaign standard. Revenue climbs to 127,500 and gross profit falls to 15,000.
Revenue up twenty-seven percent, profit down forty. The promotion gets reported as a success, because revenue is the headline number and nobody recalculated the margin. This is the most reliable way a growing business quietly stops making money, and it shows up later as the puzzle of why net margin eroded during a period when sales were strong.
When to use it
The practical use is approving discounts with a number rather than a feeling. Before any promotion, work out the volume increase required to hold gross profit and ask whether it is plausible. At a 25 percent margin a fifteen percent discount needs two and a half times the units. Most promotions do not come close, and the arithmetic takes thirty seconds.
It is also how a discount floor gets set. Once the team knows the margin, the maximum discount anyone can approve without escalation follows directly from it, and it stops being a negotiation about how much the customer wants. Where the target is expressed as markup instead, convert it first with markup to margin so the floor is set against the right number.
Clearance is a genuine exception and worth separating out. Selling aged inventory below cost can be entirely correct, because that decision is about recovering cash tied up in stock that is not moving, not about margin on the sale. Judge a markdown on inventory by what it frees up. Judge a promotional discount on live product by what it costs. Treating the two the same way is how clearance logic escapes into everyday pricing.
Where it misleads
The sale price is the least interesting output on this page. It is arithmetic anyone can do, and it is the only figure most discount calculators produce. What matters is the margin left afterwards, and that depends on a number the calculator cannot see unless you supply it.
Discounts frequently reach customers who would have paid full price. If most of the promotional volume would have arrived anyway, the promotion is a straight transfer out of profit with no volume benefit at all. Comparing promotional periods against the weeks either side is crude, but it is far better than assuming every discounted sale was incremental.
Repeated discounting resets what customers believe the product is worth. Once a predictable sale cycle exists, full-price demand collapses into the gaps between promotions, and the effective margin across the year falls even though the list price never changed. The damage accumulates slowly enough that no single promotion looks responsible.
The volume figure this calculator gives you is a break-even, not a target. Holding gross profit flat while shipping two and a half times the units means more picking, more packing, more support, and more returns for the same money. The break-even calculation understates the real cost of a promotion for exactly that reason.
Frequently asked
How much profit does a discount actually cost?
Divide the discount by the gross margin. A ten percent discount on a forty percent margin gives away a quarter of the profit. The same discount on a twenty percent margin gives away half. The lower the margin, the more expensive any given discount becomes.
How much extra volume is needed to make up for a discount?
Divide the margin by the margin minus the discount. At a forty percent margin a twenty percent discount needs twice the volume to hold the same gross profit. The required increase rises steeply as the discount approaches the margin, and once it passes it no volume is enough.
Do stacked discounts add together?
No. Twenty percent off followed by a further ten percent is twenty-eight percent off, because the second reduction applies to the reduced price. The gap widens with larger offers, which is why stacked promotions usually cost less than they appear to and confuse customers more than they persuade them.
What is the difference between a discount and a markdown?
A discount is a temporary reduction to drive demand on product that is still selling. A markdown is a permanent reduction to clear inventory that is not. They look identical on a receipt and they are different decisions: one is judged on margin, the other on the cash it releases.
Does it ever make sense to sell below cost?
Sometimes. Clearing stock that is tying up cash and warehouse space can be worth more than the loss on the sale, and a deliberate loss leader can be justified where it reliably brings profitable purchases with it. Both are specific decisions with a stated reason, not a default response to slow sales.
Numbers are the easy part
Getting the calculation right takes two inputs. Getting an organization to agree on what counts as gain, what counts as cost, and what the number should change takes considerably longer.
That translation work is most of what I do. Westphal Solutions builds websites, tools, and reporting for nonprofits and growing teams, including the kind of measurement setup that makes a number like this one worth trusting in the first place.
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