Margin With Discount Calculator
Enter your cost, your desired base margin, and the discount you plan to offer. The calculator instantly shows your original selling price, the discounted price, your true margin after the discount, your true markup, the dollar profit you keep, and the sales volume increase you need to break even on the promotion. Results update as you type.
What this calculator does
When you offer a discount, your cost stays fixed while your revenue falls. That compressed spread means your gross margin drops by more than the discount itself. This calculator lets you enter your cost, your base margin (before any promotion), and the size of the discount. It then shows you the discounted list price, your true margin, your true markup, the profit you keep per unit, and the sales volume increase you need in order to earn the same total profit as you would at full price. These five numbers together give a complete picture of what a promotional price really costs your business.
Why true margin falls faster than the discount
The key formula is: true margin = (base margin - discount) / (1 - discount). The denominator is always less than 1, so the division amplifies the numerator. For example, if your base margin is 40% and you offer a 15% discount, the true margin is (0.40 - 0.15) / (1 - 0.15) = 0.25 / 0.85 = 29.4%. The discount is 15 percentage points, but the margin drop is 10.6 percentage points, not 15. The bigger the base discount, the more severe the compression. A 30% discount on a 40% margin product leaves you with only 14.3% margin, a drop of more than 25 percentage points from a 30-point discount.
The break-even volume increase
A common mistake in planning promotions is thinking of the discount cost in revenue terms only. The more useful question is: how many more units do I need to sell to keep total profit flat? If your base profit per unit is $20 and the discounted profit per unit is $12, you need to sell 67% more units just to stay even. That break-even volume = (original profit per unit / discounted profit per unit) - 1, expressed as a percentage. This calculator works it out for you automatically. If your expected demand lift is lower than the break-even number, the promotion will reduce total profit even if it grows revenue.
Margin vs markup: what is the difference?
Margin and markup both describe profitability, but they use different denominators. Margin = (price - cost) / price. Markup = (price - cost) / cost. A 40% margin is a 66.7% markup because the denominators differ. Margin is preferred in finance and accounting because it is expressed as a fraction of revenue. Markup is common in retail because buyers and buyers agents think in terms of how much over cost they are paying. This calculator shows both before and after the discount so you can use whichever fits your workflow.
Gross margin benchmarks by industry
| Industry | Typical gross margin range | Notes |
|---|---|---|
| Software / SaaS | 70 - 85% | Low marginal cost per unit |
| Professional services | 50 - 70% | Labour-driven cost structure |
| E-commerce / retail | 30 - 50% | High logistics and returns costs |
| Food and beverage (retail) | 25 - 45% | Perishable inventory risk |
| Manufacturing | 20 - 40% | Raw material and overhead heavy |
| Grocery / supermarket | 20 - 30% | Very high volume, thin margins |
| Construction | 15 - 25% | Project variability and materials |
| Auto dealership (new cars) | 5 - 10% | Revenue from finance and service |
Typical gross margin ranges by sector. A discount that pushes your margin below your industry range means fixed costs may not be covered.
Frequently asked questions
What is the formula for margin after a discount?
True margin after discount = (base margin - discount) / (1 - discount), where both values are expressed as decimals. For example, a 40% base margin with a 20% discount gives (0.40 - 0.20) / (1 - 0.20) = 0.20 / 0.80 = 25%. You can also compute it directly: discounted price = list price x (1 - discount), profit = discounted price - cost, margin = profit / discounted price.
Does a 20% discount mean my margin drops by 20 percentage points?
No. The margin drop is always larger than the discount when expressed in percentage points, because margin is calculated on the new (lower) price. A 20% discount on a 50% margin product leaves a true margin of (0.50 - 0.20) / (1 - 0.20) = 37.5%, a drop of 12.5 points from a 20-point discount. The higher your base margin, the smaller the amplification, and the lower your base margin, the more dangerous each additional point of discount.
How many more units do I need to sell to break even on a promotion?
Break-even volume increase = (original profit per unit / discounted profit per unit) - 1. If your full-price profit per unit is $25 and your discounted profit per unit is $15, you need to sell 67% more units to earn the same total profit. If the expected demand lift from the discount is less than that, the promotion will reduce your total profit even if gross revenue rises.
What is the difference between margin and markup?
Margin = (price - cost) / price, expressed as a percentage of selling price. Markup = (price - cost) / cost, expressed as a percentage of cost. A 40% margin is a 66.7% markup. Margin is generally preferred in financial reporting; markup is common in retail buying. A discount compresses both, but the percentage-point drop looks different depending on which you are tracking.
What margin should I aim for after a discount?
That depends on your industry and cost structure. Software and SaaS businesses often target 70-80% gross margin. E-commerce and retail typically operate at 30-50%. Grocery and auto dealers run on single-digit to low-teen margins. The critical floor is your operating-expense ratio: if your true margin after discounting falls below the share of revenue consumed by fixed costs, you are making a loss on every unit even if gross profit is positive.