Discount & Sales Tax Calculator
Calculate discounted prices, sales tax, and your total savings instantly.
Interactive Client Prototype Sandbox
Disclaimer: This free tool is provided “as is,” without warranties of any kind, and is for general informational purposes only — not professional, legal, financial, medical, tax, or engineering advice. Results may contain errors; verify anything important independently and use at your own risk. We accept no liability for any loss or damage arising from its use. See our Terms of Use for details.
Step-by-Step Guide
Drag the sliders for the original price, the primary discount, an optional stacked discount, and the sales-tax rate. The final price, tax, and total savings update instantly.
$120 with 25% off, then 10% off, plus 8.25% tax ➔ final price and the exact amount saved.
Who it's for
Bargain hunters, online shoppers, sales reps, and retail workers.
Core Features
- Stack two discounts (e.g. 20% off plus an extra 10% loyalty code).
- Add any sales-tax rate with a slider.
- Step-by-step breakdown: price after each discount, tax, and final total.
- Shows your total savings and the percent saved.
🛡️ No tracking — your inputs, keys, and details never leave this client sandbox.
How do I calculate the final price after a discount?
Enter the original price and the discount percent, and the tool subtracts the discount to show the sale price, the amount saved, and — once you add a tax rate — the final price you'll actually pay.
Can I apply two discounts that stack?
Yes. The primary discount is applied first, then the optional second discount is taken off the already-reduced price (not the original). That mirrors how "extra 10% off sale prices" coupons really work, so the combined saving is a bit less than simply adding the two percentages.
Does it add sales tax?
Yes. Set your sales-tax rate and it's applied to the discounted price, with the tax amount shown separately and folded into the final total — useful for checking a register receipt before you buy.
How much am I actually saving?
The tool shows total savings as a dollar figure, so you can see the real value of stacked coupons at a glance rather than guessing from the percentages.
Why doesn't adding two discount percentages give the right answer?
Stacked discounts do not add because the second discount applies to the already-reduced price. A 20% discount followed by a 10% discount gives a combined saving of 28%, not 30%. The formula is final_price = original × (1 − d1) × (1 − d2). Each successive discount multiplies the remaining fraction, so the combined effect is always less than the sum of the individual percentages.
When is tax applied — before or after the discount?
Sales tax is applied to the discounted price, not the original price. Retailers are required to charge tax on the actual sale price. In this calculator, both discounts are applied first to find the discounted price, and then the sales tax rate is applied to that amount. The tax amount is shown separately and added to produce the final total.
A real scenario: the 30%-off sale plus a 10%-off coupon
You are standing in a store. A $200 jacket is 30% off, and you have a loyalty coupon for an extra 10% off the sale price. Your gut says you are saving 40%. You get to the register and the total is $126, not $120. You feel like you were cheated — but you weren't. The math was just not what you expected.
How stacked discounts actually work
The 30% sale brings the jacket from $200 to $140. The 10% coupon then takes 10% off $140 — that's $14 off, not $20. Final price: $126. The formula is: final_price = original × (1 − d1) × (1 − d2). Each discount is applied to the already-reduced price, not the original. The combined saving is 37%, not 40%. For any two discounts, the real combined percentage is 1 − (1 − d1)(1 − d2). Two 50%-off deals stacked give 75% off (not 100%), because the second 50% applies to what's left after the first.
How sales tax fits in
Sales tax is calculated on the discounted price, not the original. A retailer collects tax on what you actually pay, so a bigger discount reduces the tax amount too. On a $200 jacket sold at $126 with 8% tax, you pay $10.08 in tax rather than $16 — a small but real saving. The order is always: apply all discounts first, then apply tax to the discounted result.
Common mistakes to avoid
Adding discount percentages together (30% + 10% = 40%) is the most common error. The second mistake is applying tax to the original price rather than the discounted price. A third mistake appears when a coupon says "10% off the original price" rather than "10% off the sale price" — that is a different (and more generous) offer, and it does produce a 40% combined saving. Always check what the coupon's base is before calculating, especially on large purchases where the difference adds up.