How to use this calculator
Enter the original price of the item and select a discount percentage using the preset buttons or enter a custom value. The calculator instantly shows you the discount amount, the sale price, and the final price after tax.
If you have a coupon that stacks on top of an existing sale, check the "Add a second stacked discount" box and enter the additional percentage. Add your local sales tax rate to see the true out-of-pocket cost.
How stacked discounts work
A common misconception is that a 20% discount plus an extra 10% off equals 30% off. It doesn't. Stacked discounts are applied sequentially, meaning the second discount is calculated on the already-reduced price.
Example: A $100 item with 20% off, then an extra 10% off:
- First discount: $100 x 20% = $20 off, leaving $80
- Second discount: $80 x 10% = $8 off, leaving $72
- Total saved: $28 (which is 28%, not 30%)
The more discounts you stack, the larger the gap between the "simple addition" number and the actual savings. This calculator handles the math correctly so you always know your true savings.
Average sales tax by state
Sales tax rates vary widely across the United States. Here are some common rates to help you estimate your final cost:
| State | State Rate | Avg. Combined Rate |
|---|---|---|
| California | 7.25% | 8.85% |
| Texas | 6.25% | 8.20% |
| New York | 4.00% | 8.52% |
| Florida | 6.00% | 7.02% |
| Illinois | 6.25% | 8.82% |
| Pennsylvania | 6.00% | 6.34% |
| Oregon | 0.00% | 0.00% |
| Montana | 0.00% | 0.00% |
Combined rates include state, county, and city taxes. Rates are approximate and may vary by locality.
Frequently asked questions
How do you calculate a discount percentage off a price?
Multiply the original price by the discount percentage expressed as a decimal. For example, 25% off a $80 item: $80 x 0.25 = $20 discount, so the sale price is $80 - $20 = $60.
How do stacked discounts work?
Stacked discounts apply sequentially, not additively. The second discount is applied to the already-reduced price. For example, 20% off then 10% off a $100 item gives $72, not $70.
Is sales tax calculated before or after the discount?
Sales tax is calculated on the discounted sale price, not the original price. This means discounts also reduce the amount of tax you pay. If an item is originally $100 with a 20% discount, you pay tax on $80.
What is the difference between 50% off and buy one get one free?
They are mathematically equivalent if you buy exactly two items at the same price. However, BOGO requires purchasing two items, while 50% off applies to a single item. BOGO can be a worse deal if you only need one item, since you end up spending more total money.