'30% off' looks great on a tag, but what does it actually cost? This guide breaks down the discount formula, shows you how to stack multiple offers without getting fooled, and walks through real shopping scenarios. Pair it with SnapFetch's free discount calculator for instant numbers in any checkout.
The discount formula every shopper should know
There are two numbers that matter: how much you save, and what you pay. Both come from one simple percentage calculation.
Savings = Original price × (Discount % ÷ 100). Final price = Original price − Savings. That's it. Whether you're buying a $9 lipstick or a $1,499 laptop, the math is identical.
Worked examples
- 25% off a $80 jacket: savings = $20, final price = $60.
- 40% off a $129 pair of shoes: savings = $51.60, final price = $77.40.
- 70% off a $300 coat: savings = $210, final price = $90.
- 15% off a $2,499 TV: savings = $374.85, final price = $2,124.15.
Stacking multiple discounts the right way
Stacked discounts do not add. A 20% coupon on top of a 30% sale is not 50% off. Each discount is applied to the running price, not the original.
Example: a $100 jacket at 30% off becomes $70. A 20% coupon on $70 is $14. Final price = $56. Total discount = 44%, not 50%.
This is why retailers love stacked promotions — they sound bigger than they are. Always apply discounts sequentially to know the real number.
Quick mental shortcut: multiply the discount multipliers. 30% off then 20% off = 0.70 × 0.80 = 0.56, meaning you pay 56% of the original.
Discounts with sales tax or VAT
In the US, sales tax is added after the discount: $100 jacket at 30% off = $70, plus 8% tax = $75.60.
In the UK and EU, VAT is already included in the displayed price. A 30% discount applies to the gross price, and the VAT inside it shrinks proportionally.
Common retailer tricks to watch for
- Inflated 'original' prices that no one has paid in months — the discount is from a fake anchor.
- Bundle discounts that only apply if you buy three of an item you wouldn't buy two of.
- Free shipping thresholds that push your basket past the value of the discount you're chasing.
- Member-only prices that require a $99/year subscription to unlock $20 of savings.
Use our free discount calculator
When the math gets messy in a real checkout, switch to SnapFetch's free discount calculator. Enter the original price and the discount percent — savings and final price update instantly. Copy either number with one tap.
Try our free discount calculator the next time you're shopping a sale.
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