How discounts actually work — and why stacking them isn't what you think
A discount is a reduction from the original price. The three most common questions are: what is the final price after a known % off, what % off was applied given two prices, and what % does a fixed rupee saving represent. Each has a formula.
Percentage discount
Formula: Savings = Original × (Discount% ÷ 100) · Final price = Original − Savings
Examples:
- 25% off ₹3,200: savings = 3,200 × 0.25 = ₹800 → final price ₹2,400
- 15% off ₹499: savings = ₹74.85 → final price ₹424.15
The savings bar in this tool fills proportionally — a 25% discount fills 25% of the bar in green, so you immediately see how significant the saving is.
Finding the discount percentage from two prices
Formula: Discount% = ((Original − Final) ÷ Original) × 100
This is useful when a store shows "was ₹1,800, now ₹1,350" without stating the percentage.
- Saving = 1,800 − 1,350 = ₹450
- Discount% = (450 ÷ 1,800) × 100 = 25%
Always divide by the original price, not the final price. Dividing by the final gives a different (larger) figure — a common mistake in vendor claims.
Stacked discounts: why 20% + 10% ≠ 30%
Stacked discounts apply one after another, not on the original price together.
- 20% off ₹1,000 → ₹800
- 10% off ₹800 → ₹720 (not ₹700)
- Total saving: ₹280, which is 28% off the original — not 30%
The formula for two stacked discounts: Total% off = 100 − (100 − d₁) × (100 − d₂) ÷ 100
For 20% and 10%: 100 − (80 × 90 ÷ 100) = 100 − 72 = 28%
This is why "extra 10% off already discounted items" is always less impressive than it sounds.
MRP vs sale price — what the label means
In India, MRP (Maximum Retail Price) is the legally required maximum. A product selling at "40% off MRP" means the store is charging 60% of the printed price. The discount is always calculated on MRP, not on a fictitious "market price" — so be skeptical when discounts are claimed against an inflated "original" price.