How Discounts Are Calculated
Sale price = Original × (1 − discount %)
A $79.99 item at 30 % off costs 79.99 × 0.70 = $55.99 — you save $24.00.
Stacked Discounts Don't Add Up
"30 % off + extra 10 %" is not 40 % off. The extra discount applies to the already-reduced price: 79.99 × 0.70 × 0.90 = $50.39, an effective 37 % discount. Retailers know the difference — now you do too. This calculator has a dedicated field for the extra discount and shows your true effective percentage.
Quick Mental Math at the Sale Rack
- 10 %: shift the decimal — $45.90 → $4.59 off.
- 25 %: quarter the price. 50 %: halve it. 75 %: halve twice, then a bit more (¾ off = quarter price).
- Compare absolute savings, not percentages: 40 % off a $30 shirt saves $12; 15 % off a $200 jacket saves $30.
Discount vs. Markup — Not Symmetrical
A price cut of 20 % needs a 25 % increase to return to the original. That asymmetry is why "was $100, now $80, back to $100" is a 25 % markup on the sale price — and why percent math around pricing deserves a second look.