Discount Calculator
Four discount questions, one tool: take a percentage off, take a fixed dollar amount off, work backwards from a sale price to the original, or add sales tax on top of a discounted price. If your question is a percentage discount with a second discount stacked at the till, the Percent Off Calculator is the one built for that.
Your result will appear here
Choose a mode, enter your numbers, then click calculate.
More than percent off
Looking for just a quick percent-off number? Use our simpler Percent Off Calculator. This Discount Calculator is the broader version — four modes, including a fixed dollar amount off, a reverse solve for the original price, and tax applied after the discount.
This tool or the Percent Off Calculator?
They overlap on one mode and diverge everywhere else, so the split is simple.
- Use this one for a fixed dollar amount off, for working backwards from a sale price, or for adding sales tax after the discount. Four modes, one discount at a time.
- Use the Percent Off Calculator when two discounts stack — 40% off, then an extra 10% at the till. That is the one thing it does that this tool does not, and it is the case most often got wrong.
The Four Modes, and When Each Is the Right One
Percentage off — the ordinary case. A $120 jacket at 25% off is $120 × 0.75 = $90, saving $30.
Fixed amount off — when the sign says “$45 off” rather than a percentage. On a $180 item that leaves $135, and the tool also tells you it was a 25% discount, which is what you need to compare it against a percentage offer elsewhere. A flat amount is a bigger discount on a cheaper item, which is easy to lose sight of.
Reverse: original price from a sale price — when the tag shows the sale price and the percentage but not what it was before, or when you want to check a “was” price. Divide rather than subtract: a $75 sale price at 25% off started at $100. Adding 25% back to $75 gives $93.75, which is a different and wrong number, because the percentage was taken off the larger figure.
Tax after discount — for the amount you actually hand over. In almost every US state sales tax is charged on the discounted price, so a discount saves you the tax on it too. A $120 item at 25% off with 8.25% sales tax comes to $97.43: $90 after discount, plus $7.43 of tax.
Stacked Discounts Multiply, They Never Add
This tool applies one discount at a time. The reason it is worth spelling out anyway is that two discounts are the case people get wrong, and the error always runs the same way — in the shop’s favour in your head, and against your expectations at the till.
Two discounts multiply. 40% off followed by an extra 10% is 0.60 × 0.90 = 0.54, so you pay 54% of the original and the effective discount is 46%. It is not 50%.
On an $84.99 item: 40% off brings it to $50.99, then 10% off that is $45.89. Treating the two as a straight 50% would have predicted $42.50 — $3.39 too optimistic. The order makes no difference; 10% then 40% lands on the same $45.89.
For stacked discounts use the Percent Off Calculator, which takes a second percentage directly.
Quick Answer
Pick the direction you need. Percentage off: multiply by (100 − percent) ÷ 100, so 25% off $120 is $90. Fixed amount off: subtract, then divide by the original to see what percentage it was — $45 off $180 is $135, which is 25%. Reverse: divide rather than subtract, so a $75 sale price at 25% off started at $100. Tax after discount: apply the discount first, then the tax rate to the reduced price.
How It Works: Formula & Variables
Discount = Original × (Percent Off / 100) · Final = Original − Discount
- Percent off
- Discount = Original × (Percent / 100); Final = Original − Discount.
- Fixed amount off
- Final = Original − Discount($); the equivalent percent off is Discount($) / Original × 100.
- Reverse (find original)
- Original = Sale Price / (1 − Percent Off / 100).
- Tax after discount
- Total = Final Price × (1 + tax rate / 100), with tax charged on the discounted price.
Source: our own Percent Off Calculator, which documents the base percent-off math.
Worked Examples
Example 1: Percentage off
A $120 jacket at 25% off. The discount is $120 × 0.25 = $30, so you pay $90.
Example 2: Fixed amount off, converted to a percentage
“$45 off” on a $180 item leaves $135. As a percentage that is $45 ÷ $180 = 25% — the same discount as Example 1, expressed the other way. Converting is the only way to compare a dollar-off offer against a percentage-off one.
Example 3: Working back to the original price
A tag reads $75 and “25% off”, with no original price. Divide: $75 ÷ 0.75 = $100 before the discount, a $25 saving. Adding 25% back onto $75 would give $93.75, which is wrong — the percentage came off the larger number, so it has to be divided out of the smaller one.
Example 4: What you actually pay at the register
The same $120 jacket at 25% off, in a jurisdiction charging 8.25% sales tax. The discount applies first, giving $90, then tax on that: $90 × 0.0825 = $7.43, for a total of $97.43. Had the tax been charged on the full $120 first, you would pay $2.48 more — which is why the order matters and why almost every state taxes the discounted price.
Key Concepts
Percent depends on the price, a fixed amount doesn't: $30 off is always $30, but 25% off saves more the pricier the item.
Reverse math needs division, not subtraction: To recover an original price you divide by (1 minus the discount), which is why the original is always higher than a naive add-back would suggest.
Tax lands on the discounted price: Discount first, then tax on what's left — that ordering keeps the total honest.
Common Mistakes
Adding discount percentages together: 40% off plus 10% off is not 50% off, because the second discount applies to the already-reduced price.
Confusing the final price with the discount amount: What you save and what you pay are two different numbers.
Taxing the original price instead of the discounted one: Applying tax before the discount inflates the total.
Frequently Asked Questions
It means you pay 75% of the original price. The discount is 25% of the price, and what's left is the three-quarters you actually hand over.
Divide the sale price by (1 minus the discount as a decimal). A $75 sale price at 25% off means $75 divided by 0.75, which is a $100 original price.
No. The second discount comes off the already-reduced price, not the original. So 40% off and then 10% off is not 50% off — it works out to less, because the 10% is taken from a smaller number.
Usually after. The discount comes off first, and the tax or VAT is then calculated on the reduced price, not the original.
A fixed amount comes straight off the price — $30 off is $30 off no matter the price. A percentage depends on the original price, so the same percent saves you more on a pricier item.
Divide the discount amount by the original price and multiply by 100. A $30 discount on a $120 item is 30 / 120 x 100, which is 25% off.
Related Calculators
Need your own local tax rate?
The tax mode above takes whatever rate you type. To find the combined state and local rate that applies where you are shopping, use the sales tax calculator, or the VAT calculator where prices are quoted with tax already included. For two discounts stacked at the till, the percent off calculator handles both at once.
Assumptions
- Amounts are rounded to the nearest cent at the end of the calculation. A retailer rounding at a different point can land a cent away.
- Sales tax is applied to the discounted price, which is the rule in almost every US jurisdiction. A few coupon types are treated differently by state law; the receipt is the authority.
- One discount at a time. Two stacked discounts multiply rather than add — see above, and use the percent off calculator for that case.
- No allowance for store-specific caps, exclusions on already-reduced items, or membership pricing.