What will you actually pay after the discount and the sales tax?
Short answer: The Discount & Tax Calculator takes a percentage off the price first, then adds sales tax to the reduced amount: final price = price × (1 − discount%) × (1 + tax%). It rounds to whole cents at each step. For $100 at 20% off with 8.25% tax, it shows $20.00 saved, $80.00 after discount, $6.60 tax and an $86.60 final price.
Key facts
- The calculator has four inputs: Original price, Discount (%), Sales tax (%) and Currency.
- The form starts with a price of 100, a discount of 10%, a sales tax of 0% and USD, so tax stays at zero until you change it.
- The Original price field accepts 0.01 up to 1,000,000,000, and both percentage fields accept 0 to 100 inclusive; anything else shows an error instead of a result.
- Sales tax is always calculated on the price after the discount, never on the original price.
- The result panel lists five lines: Original price, Discount saved, Price after discount, Tax and Final price.
- The Currency menu offers USD, EUR, GBP, CAD, AUD, CHF and RUB, and it only changes how amounts are formatted; no exchange rate is applied.
- The calculation runs in your browser and the script makes no network requests, so the prices you type are not uploaded.
How to use
- Type the shelf price into Original price, before any coupon or tax.
- Enter the sale or coupon percentage in Discount (%) and your local rate in Sales tax (%). Leave tax at 0 if the price already includes it.
- Pick a Currency, then press Calculate price.
- Read the Final price line. If you edit any field, the old result disappears, so press Calculate price again.
Formula and rounding
Every amount is handled in whole cents. The discount and the tax are each rounded once, with half a cent rounding up.
price_c = round(price × 100)
discount_c = round(price_c × discount / 100)
subtotal_c = price_c − discount_c
tax_c = round(subtotal_c × tax / 100)
final = (subtotal_c + tax_c) / 100Here price is in your chosen currency, discount and tax are percentages, and the suffix _c means cents.
Worked example
These rows were produced by running the calculator's formula with the inputs shown.
| Original price | Discount | Sales tax | Discount saved | Price after discount | Tax | Final price |
|---|---|---|---|---|---|---|
| $100.00 | 20% | 8.25% | $20.00 | $80.00 | $6.60 | $86.60 |
| $249.99 | 15% | 7% | $37.50 | $212.49 | $14.87 | $227.36 |
| $64.50 | 30% | 6.5% | $19.35 | $45.15 | $2.93 | $48.08 |
| $19.99 | 25% | 8.875% | $5.00 | $14.99 | $1.33 | $16.32 |
| $100.00 | 100% | 8% | $100.00 | $0.00 | $0.00 | $0.00 |
Does the order of discount and tax matter?
When both are plain percentages applied one after the other, the final price is the same in either order, because multiplication does not care about order. What changes is the tax line: tax on the sale price is smaller than tax on the original.
The real gap appears when a seller taxes the pre-discount price, which can happen with some kinds of coupons. On $100 with 20% off and 8.25% tax, that gives $80.00 + $8.25 = $88.25 instead of $86.60. The calculator only models discount-first, so check the receipt if the numbers differ.
Fixed-dollar coupons and stacked discounts
The tool has no field for a coupon worth a flat amount. Divide the coupon by the price and multiply by 100 to get a percentage. A $10 coupon on a $64 item is 15.625%, and entering that gives $54.00 after discount.
Two percentage discounts do not add up. Run the calculator once with the first discount and tax at 0, then use its Price after discount as the new Original price. 20% off followed by 10% off turns $100 into $72, which is 28% off in total, not 30%.
Why a basket can be a cent off
Stores round tax per item or per order, and this calculator rounds the whole entered price once. Take three $19.99 items at 10% off with 8.25% tax. Each item comes to $19.47, so $58.41 item by item. Entered as one $59.97 purchase, the same inputs give $58.42.
What this tool does not do
- The calculator handles one price, one percentage discount and one tax rate; shipping, service fees, deposits and exempt items are not included.
- The tool does not look up tax rates, decide what is taxable or interpret coupon rules, and it is not tax advice.
- The calculator works forward only, so it cannot find the original price or the discount from a final price.
- The Currency menu does not convert money between currencies.
Frequently asked questions
How do I calculate sales tax after a discount?
Subtract the discount from the price first, then multiply the reduced price by the tax rate and add the result. For $100 at 20% off with 8.25% tax, the discounted price is $80.00, the tax is $6.60 and the total is $86.60.
Is sales tax charged on the original price or the discounted price?
It depends on the seller and local rules, and this calculator assumes the discounted price. Some coupons, such as ones reimbursed by a manufacturer, may be taxed on the pre-discount price in some places. Check your receipt or official local guidance for a specific purchase.
How much is 20% off $100 with 8.25% tax?
The final price is $86.60. Twenty percent of $100 is $20.00, leaving $80.00, and 8.25% of $80.00 is $6.60. Shipping and other fees are not included.
Does the calculator include shipping, fees or several coupons?
No. It handles one price, one percentage discount and one tax rate. Shipping, service fees, deposits, exempt items and extra coupons need separate calculations.
How do I enter a fixed-dollar coupon?
Convert it to a percentage by dividing the coupon by the price and multiplying by 100. A $10 coupon on a $64 item is 15.625%, which gives a $54.00 discounted price.
How do I apply two discounts in a row?
Run the calculator twice and use the first Price after discount as the second Original price, with tax at 0 on the first run. 20% off followed by 10% off turns $100 into $72, which is 28% off in total.
Why does my checkout total differ by a few cents?
Stores may round tax per item or per order, and baskets can mix tax rates. This calculator rounds the discount and the tax once each, so three $19.99 items at 10% off with 8.25% tax come to $58.41 item by item but $58.42 as one $59.97 purchase.
Does the calculator send my prices anywhere?
No. The calculation runs in your browser and the calculator script makes no network requests, so the numbers you type are not uploaded.
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