How Discounts Affect Profit: The Math Behind a “10% Off” Sale
A 10% discount does not mean you lose 10% of your profit. If your costs stay the same, the percentage reduction in profit can be much larger.
For example, a product sold for ₹1,000 with a variable cost of ₹600 earns ₹400 per sale. A 10% discount reduces the price to ₹900 and profit to ₹300.
So, a 10% discount has reduced profit per sale by 25%. You now need about 33.33% more sales to earn the same total profit.
How to Calculate the Profit Impact of a Discount
Use these formulas:
Profit per unit = Selling Price − Variable Cost
Discounted Price = Selling Price × (1 − Discount %)
Discounted Profit = Discounted Price − Variable Cost
Example: A 10% Discount on a ₹500 Café Meal
Suppose a café sells a meal for ₹500. Ingredients, packaging and other variable costs total ₹300.
- Original profit = ₹500 − ₹300 = ₹200
- Original profit margin = ₹200 ÷ ₹500 × 100 = 40%
- 10% discount = ₹50
- Discounted price = ₹450
- Discounted profit = ₹450 − ₹300 = ₹150
- New profit margin = ₹150 ÷ ₹450 × 100 = 33.33%
Profit per sale has fallen from ₹200 to ₹150.
Profit reduction = (₹200 − ₹150) ÷ ₹200 × 100 = 25%
How Many More Units Must You Sell?
Suppose the café normally sells 100 meals:
100 × ₹200 = ₹20,000 contribution.
After the discount, each meal contributes ₹150. To generate the same ₹20,000:
Required units = ₹20,000 ÷ ₹150 = 133.33
So the café must sell about 134 meals instead of 100 — an increase of roughly 33.33%.
Required Units After Discount = Original Profit per Unit ÷ Discounted Profit per Unit × Original Units
If discounted profit per unit becomes zero or negative, selling more of that product cannot recover the lost product-level profit.
Why Low-Margin Products Are Especially Vulnerable
Consider a product selling for ₹1,000 with a variable cost of ₹900.
- Original profit = ₹100
- Original margin = 10%
A 10% discount makes the selling price ₹900.
New profit = ₹900 − ₹900 = ₹0
A 5% discount is also serious: the price becomes ₹950 and profit falls to ₹50. You would need to sell twice as many units to generate the same total contribution.
The lower your margin, the less room you have to absorb a discount.
When Can a Discount Make Sense?
Discounting can make sense when extra sales or related purchases generate more contribution than the amount sacrificed through the lower price.
For example, a café may discount a slow weekday item to use spare capacity, or a retailer may discount ageing inventory to recover cash. The question is not simply whether the promotion increases sales.
The question is whether the extra sales generate enough profit to compensate for the lower profit per sale.
Calculate Before You Announce the Sale
Test the original price and discount level before launching the promotion. Compare profit per unit, margin and the extra units required to maintain total profit.
Pricing & Discount Impact Calculator
See what price you need to achieve your target margin and how a discount affects your profit, margin, and required sales volume.
For related pricing decisions, read How to Price a Product in India, Markup vs Margin in India and What Is Gross Margin?. If fixed costs are important to your calculation, use the Break-Even Calculator.
Further Reading
Do the Math First: 25 Numbers to Calculate Before Starting a Business by Kajal Mandal is useful for building a habit of checking business numbers before pricing and growth decisions.
Frequently Asked Questions
How much profit is lost from a 10% discount?
It depends on the original margin. At ₹1,000 price and ₹600 cost, profit falls from ₹400 to ₹300, a 25% reduction.
How many extra units must I sell after a discount?
Divide original profit per unit by discounted profit per unit. ₹400 ÷ ₹300 means about 33.33% more units.
Why is discounting dangerous at low margins?
A low-margin product has less profit available to absorb a price reduction, so a modest discount can eliminate much of the profit.
Does a 10% discount reduce profit by 10%?
No. The percentage reduction in profit depends on your original selling price and variable cost. It can be much larger than 10%.
The Bottom Line
Before offering any discount, calculate three numbers: profit per discounted sale, percentage of profit lost, and extra units required to recover it.
If you cannot calculate those numbers, you are not pricing a promotion — you are guessing.