How to Calculate a Discount
Calculating a discount comes down to two steps: figure out the dollar amount you save, then subtract that from the original price. The formula is savings = original × (percent / 100) and sale price = original − savings. For example, 30% off a $50 shirt saves $15, so you pay $35.
Quick Mental Math Tricks
- 10% off: Move the decimal one place left. $40 → $4 off → pay $36.
- 25% off: Divide by 4 to find savings. $80 / 4 = $20 off → pay $60.
- 50% off: Half price. $90 → pay $45.
- 75% off: Pay one quarter of the original. $80 → pay $20.
Where Sales Tax Fits In
In the United States, sales tax is applied to the discounted price, not the original. That means a deeper discount also reduces the tax you pay. Enter your local sales tax rate above to see the true checkout total. The actual rate varies by state, county, and sometimes city — typically 6% to 10% combined.
Stacked Discounts: 50% + 20% Is Not 70%
When stores apply "extra 20% off the sale price," the second discount works on the already-reduced amount. A $100 item at 50% off becomes $50; another 20% off brings it to $40 — a 60% total discount, not 70%. The math: 1 − (0.5 × 0.8) = 0.6, or 60% off.
When the Discount Looks Big But Isn't
Watch for inflated "original prices." A retailer that lists a $200 MSRP and sells for $99 may always sell it at $99. Compare against verified historical prices or check competitor pricing before assuming the discount represents real savings.