Discount and Sales Tax Calculator with Stacked Coupons
$100 at 60% off plus 5% sales tax comes to $42. Stack coupons and clearance discounts, add your state's sales tax and see what you save.
Stacked discounts and US sales tax: working out the final price
Two successive discounts multiply rather than add: 30% then 15% gives 40.5% off, not 45%. US sales tax is then applied to the discounted price; at 8.25%, a $120 item ends up costing $77.29.
Formula
- Price after the first discount:
P1 = price × (1 − r1). - Subtotal after the coupon:
P2 = P1 × (1 − r2). - Effective discount:
1 − (1 − r1) × (1 − r2). - Tax:
P2 × rate; total = P2 + tax.
Example
A $120 item, 30% off then a 15% coupon. First discount: $36.00, price $84.00. Coupon: 15% of 84.00 = $12.60, subtotal $71.40. Savings: $48.60, or 40.5%. Tax at 8.25%: $5.89. Total: $77.29. Two 50% discounts do not make the item free: 25% of the price remains.
Which tax rate to enter
US sales tax is not federal: each state sets a rate, and counties and cities often add their own. There is no national rate, and a few states levy none at state level. The 8.25% default is the maximum combined rate in Texas (6.25% state plus up to 2% local). Enter the combined rate for the place of purchase, shown on the receipt or by the state tax agency.
Limits
The tool applies tax after all discounts. In some states a manufacturer’s coupon (reimbursed to the store) does not reduce the taxable price, and some goods such as groceries or clothing are taxed at a lower rate or exempt. Amounts are rounded to the cent.
Sources and dates: Texas Comptroller, Sales and Use Tax: 6.25% state rate, up to 2% local tax, 8.25% maximum combined rate (checked 14/10/2026).
Frequently Asked Questions
Do 30% and 15% discounts add up to 45%?
No, they multiply: 0.70 × 0.85 = 0.595, a real discount of 40.5%. On $120, the pre-tax price becomes $71.40.
Is sales tax calculated before or after the discount?
For a store discount, tax applies to the reduced price. In some states a manufacturer’s coupon does not reduce the taxable amount; the tool applies tax after all discounts.
What is the sales tax rate in the United States?
There is no national rate: each state sets its own and local governments add theirs. In Texas the state rate is 6.25% and the total can reach 8.25% with local taxes.
How do I find the original price from the sale price?
Divide what you paid by the product of the remaining factors. An item bought for $71.40 after 30% and then 15% off was $71.40 / (0.70 × 0.85) = $120.
Is this tool really free?
Yes, all tools on Kristools are 100% free and accessible without registration.
Is my data protected?
Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.