Discount and Sale Price Calculator
Sale price, savings, and total with tax and quantity for any percent off deal.
What it does
A percent off deal is one multiplication. The sale price equals the original times one minus the discount rate. Tax then applies to the reduced price in most places, so the register total runs lower than taxing first.
The tool above follows that order: discount first, then tax, then quantity. It prints the per unit sale price, the per unit saving, and the full total so bulk deals stay clear.
Watch stacked offers with care. Two discounts of 20% and 10% do not make 30% off. The second cut applies to the already reduced price, landing at 28% off combined.
How to use
- Enter the original price from the tag, not a crossed out anchor price you cannot verify.
- Enter the discount percent from the offer.
- Enter local sales tax, or zero when comparing pre-tax prices.
- Set quantity to price multi unit deals, then read the total.
Formula
- keep rate
- One minus discount. 25% off keeps 0.75.
- tax rate
- Applied to the reduced price, usually.
- quantity
- Units multiplied after tax per unit.
Convert the percent to a rate first: 25% off means keep 75%, so multiply by 0.75. Stacked discounts multiply keep rates: 20% then 10% is 0.80 x 0.90 = 0.72, which is 28% off, not 30%.
Worked example
Example: $120 jacket, 25% off, 8% tax, two units
Original 120, discount 25%, tax 8%, quantity 2.
- Keep rate: 1 - 0.25 = 0.75.
- Sale each: 120 x 0.75 = $90.00.
- Saving each: 120 - 90 = $30.00.
- With tax each: 90 x 1.08 = $97.20.
- Total for two: 97.20 x 2 = $194.40.
Reference table
| Discount | You pay | You save |
|---|---|---|
| 10% off | $90.00 | $10.00 |
| 20% off | $80.00 | $20.00 |
| 25% off | $75.00 | $25.00 |
| 30% off | $70.00 | $30.00 |
| 50% off | $50.00 | $50.00 |
Limits
- State tax rules vary for specific goods.
- Anchor prices may be inflated, shrinking real savings.
- Coupons may exclude sale items or stack differently.
- Shipping and returns sit outside the math.
Common mistakes
- Trusting inflated anchor prices that make the percent look bigger than the real cut.
- Adding stacked percents instead of multiplying keep rates.
- Forgetting tax and shipping when comparing two deals.
- Rounding the sale price before multiplying quantity, which drifts on large orders.
- Buying extra units for a threshold discount that costs more than the saving.
Try it yourself
Quick checks. Answers sit tucked under each question.
$80 with 30% off, no tax?
Keep 0.70. Sale $56.00, saving $24.00.
Stacked 20% then 10% on $100?
0.80 x 0.90 = 0.72, so $72. That is 28% off, not 30%.
Questions
Is tax charged before or after the discount?
After, in most US states: the register taxes the reduced price. A few places differ for specific goods, so the receipt is the final word.
How do stacked coupons combine?
Multiply the keep rates. A 20% code plus 10% off is 0.80 x 0.90 = 0.72 of the price, which is 28% off.
What does 30% off plus an extra 10% mean?
It means 0.70 x 0.90 = 0.63, so 37% off total, not 40%.
How do I reverse a sale price to the original?
Divide by the keep rate. A $90 sale at 25% off came from 90 / 0.75 = $120.
Why does the total differ by a cent from my math?
Rounding. Registers round per line or at the end per store policy, so a cent of drift is normal.