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Discount Calculator
What does the sale price really come to? This discount calculator shows the final price and your savings, stacks a double or triple discount, adds sales tax, and can reverse-solve the original price from a sale price. Every change recalculates as you type.
See how this works on a $100 sticker price — 3 real examples
Final price you pay
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You save
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Effective discount
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Pre-tax price
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Of the original price (—):
Discount waterfallEach discount applied to the running price, step by step
| Step | Discount | Price after | Saved this step |
|---|
How your stacked discount, final price and tax are calculated
A single discount is straightforward, but stacked discounts and tax have to be applied in the right order:
% off: price → price × (1 − rate/100)
$ off: price → max(0, price − amount)
You save = original − final Effective % = 100 × saved / original
After tax = final × (1 + tax/100)
In Apply discounts mode each row is applied to the running price, not the original — so 20% off then an extra 15% off takes $100 to $80 and then to $68, an effective 32% off rather than 35%. Percentage discounts multiply; fixed-dollar discounts subtract and are floored at zero so a price never goes negative. Only after every discount is applied do we add sales tax, because tax is charged on the discounted price you actually pay. In Find the discount mode we run the same relationship backward: given the original and sale price, the effective discount is (original − sale) / original. The sales-tax field is a rate you enter for a plain after-tax total — this tool does no government tax-liability math. It is for planning and education, not financial advice.
The $100 sticker, three ways to cut it
A 20%-then-15% stack, a straight 35%, and the same stack with tax added — three answers a sale tag will not volunteer.
The stack: 20% off, then an extra 15%
final price$68.00
- The first cut takes the $100 sticker to $80; the second works on that $80, not the original.
- The extra 15% is worth $12 here — the same rate on the full price would be $15.
- Together they come to an effective 32% off, three points short of the 35% the tag implies.
Stacked percentages multiply, they never add — the second discount works on smaller money.
Load this example (opens in a new tab)The claim on the tag: a straight 35%
final price$65.00
- One 35% discount off $100 lands at $65 — $3 below where the stack stops.
- All $35 of savings comes off the full price, which is the whole difference.
- For the stack to match it, the extra cut would need to be 18.75%, not 15%.
“20% plus an extra 15%” sounds like 35% — the register knows it is 32%.
Load this example (opens in a new tab)At the register: the stack plus 8% tax
after-tax total$73.44
- Tax is charged on the $68 you pay, not the $100 sticker — $5.44 instead of $8.
- The discounts save $32 before tax, and the checkout total settles at $73.44.
- Discounting first shaves $2.56 off the tax bill itself, on top of the price cut.
The order is fixed in your favor: discount first, then tax on what is left.
Load this example (opens in a new tab)Illustrations only, not financial advice. Your own rate, taxes and insurance will differ — check with a qualified financial advisor before acting on any of this.
Reading a sale sticker, in plain English
- Stacked discounts don't add up. 20% then 15% is 32% off, not 35% — the second cut only ever comes off the already-reduced price.
- Order matters with fixed-dollar deals. A $10-off coupon is worth the same either way, but a percentage taken before it is charged on the higher price, so a bigger percent-first order saves you more.
- Tax comes last. You are taxed on what you pay, not the sticker, so discounting first and taxing second is the correct — and cheaper — sequence.
- Percent-off scales, dollar-off doesn't. 25% off is bigger on pricier items; a flat $20 off is a better deal on cheap ones.
- Reverse it to check a claim. Enter the original and the sale price to see the true percentage off — handy when a tag says "up to 70% off."
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Frequently asked questions
How do I calculate the final price after a percentage discount?
Multiply the original price by one minus the discount as a decimal: final = price × (1 − discount%/100). A $100 item at 20% off becomes 100 × (1 − 0.20) = $80, and you save the other $20. This discount calculator does that instantly and also shows the effective percentage and, if you add a rate, the after-tax total.
How do stacked discounts work — 20% off then an extra 15% off?
Stacked (successive) discounts apply one after another to the running price, so they do not simply add up. 20% off $100 leaves $80; taking an extra 15% off that $80 leaves $68 — an effective 32% off, not 35%. Each percentage is charged on the smaller amount left after the previous one, which is why a double discount always saves less than the two rates added together.
How do I find the original price from a sale price and discount?
Switch to “Find the discount” mode and enter the original price and the sale price — the calculator returns the effective discount percentage and the dollars saved. To go the other way and recover the original from a known sale price and percentage, divide: original = sale ÷ (1 − discount%/100). A $80 shirt that was 20% off started at 80 ÷ 0.80 = $100.
How do I add sales tax to the discounted price?
Tax is charged on the discounted price, not the original, so discount first and tax second. Enter your sales-tax rate in the optional field: the tool applies it to the final pre-tax price and shows the after-tax total. On a $68 discounted price at 8% tax, you add $5.44 for a $73.44 checkout total. The rate is one you enter — this is plain arithmetic, not a government tax computation.
What is the difference between a percent-off and a fixed-amount-off discount?
A percent-off discount scales with the price — 25% off is $25 on a $100 item but $50 on a $200 item. A fixed-amount-off discount subtracts the same dollars regardless of price, so $20 off is worth more on cheaper items. This calculator lets you mix both in one stack: pick “% off” or “$ off” on each row, and it applies them in order down to a floor of zero.
How do I calculate what percentage discount I received?
Divide the amount saved by the original price and multiply by 100: effective discount% = (original − final) ÷ original × 100. If a $120 jacket cost you $90, you saved $30, which is 30 ÷ 120 = 25% off. In “Find the discount” mode this calculator does the division for you from any original-and-sale-price pair.
Disclaimer: these calculators are educational tools, not financial advice. They model your inputs with published formulas, but they cannot know your full situation — for decisions with real stakes, talk to a qualified professional. Formulas and defaults last reviewed .