Discount savings and the price after tax
The main answer is the quantity you chose to find. The breakdown shows the original price, total discount savings, price before tax and final checkout price. Effective reduction compares the tax-inclusive final price with the original price.
For a restaurant bill after a discount, enter the resulting pre-tax subtotal in the Tip Calculator to calculate gratuity and each person’s share.
The formula
For two discounts, multiply the remaining-price factors: Original × (1 − First/100) × (1 − Additional/100). Subtract the coupon amount, stopping at zero, then apply tax. To reverse the discounts, add the coupon to the sale price and divide by the remaining-price factors. Discount percentage is (Original − Sale) ÷ Original × 100.
Worked example
A 100 item at 20% off costs 80 before tax. With 10% tax on 80, the final price is 88—12% below the original price.
How to use this calculator
- Choose Sale price, Original price or Discount %.
- Enter the two requested values. Original price and Discount % modes use a sale price before tax.
- Open Advanced options to apply a second percentage discount, subtract a coupon amount or add tax. The additional discount and coupon apply in sale and original price modes.
- The answer updates as you type. Calculate updates immediately; Reset restores the example.
Discount before tax
Retail systems commonly apply eligible discounts before calculating sales tax, but local rules can differ.
The optional tax field is a simple percentage of the discounted subtotal.
Stacked discounts
A further 10% off an already discounted 80 removes 8, not 10 from the original 100.
Two discounts of 20% and 10% combine to 28%, because 0.8 × 0.9 leaves 72%.
Enter 20 as the first discount and 10 as Additional discount to calculate this directly. A coupon amount is subtracted after both percentage discounts. For example, another 5 off the resulting 72 leaves 67 before tax.
Assumptions & limitations
What this calculation assumes
- Percentage discounts are applied sequentially, then a coupon amount is subtracted.
- Tax is applied to the discounted subtotal. Sale prices entered for reverse calculations exclude tax.
- All amounts use the same currency. Intermediate results are not rounded to cents.
What to keep in mind
- Shipping, quantity promotions and jurisdictional tax rules are excluded.
- A 100% percentage discount cannot be reversed to a unique original price. A zero sale price with a positive coupon is also ambiguous.
- Coupon savings stop at the price of the item; the checkout amount cannot become negative.
- Effective reduction can be negative if tax exceeds savings. Retail rounding may differ by a cent.
Common questions
How do I combine two discounts?
Enter the first percentage as Discount and the second as Additional discount under Advanced options. The calculator applies them sequentially: 20% and then 10% off 100 leaves 72, a total saving of 28.
Is tax part of the amount saved?
No. Savings reports the discount; effective reduction accounts for tax.
Can a discount exceed 100%?
This calculator limits discount to 100%.
How do I find the original price?
Choose Original price and enter the sale price before tax and the discount percentage. For example, a sale price of 80 after 20% off gives an original price of 100. Add any extra discount or coupon under Advanced options.
How do I use a coupon for a fixed amount?
Enter the coupon value under Advanced options. It is subtracted after the percentage discounts and before tax. For a fixed coupon alone, enter 0 as the percentage discount.
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