The core formula
A 20% discount followed by another 10% does not equal 30% off. An item priced at 100 becomes 80 and then 72, an effective discount of 28%.
Worked example
20% off $100 gives $80; another 10% off gives $72.
How to calculate a discount
- Convert the discount percentage to a decimal and multiply it by the original price to find savings.
- Subtract the savings from the original price to get the sale price.
- For sequential discounts, apply the second discount to the already discounted price.
- Apply fixed-value coupons according to the retailer rules, then calculate tax on the correct taxable amount.
Why stacked discounts are not simply added
Two percentage discounts usually apply one after the other. For example, 20% off followed by 10% off reduces a $100 price to $80 and then $72, which is an effective 28% discount rather than 30%.
Retailer rules can change the order of coupons, loyalty credits and tax. The calculator handles the arithmetic you specify; verify the transaction rules when exact checkout pricing matters.
Common mistakes
- Adding sequential discount percentages as if they share the same price base.
- Applying a fixed coupon before a percentage discount when the retailer applies it after.
- Calculating tax from the wrong taxable amount.
Use the calculator
Calculate sale price, savings, stacked discounts and effective discount percentage.
Open Discount CalculatorApply sequential discounts multiplicatively
A 20% discount followed by another 10% does not equal 30% off. An item priced at 100 becomes 80 and then 72, an effective discount of 28%.
Separate coupons from percentage discounts
A fixed-amount coupon usually reduces the post-discount price, but retailer terms, minimum spend and tax calculations can affect ordering. Verify what the offer actually applies to.
Frequently asked questions
Is 20% off plus 10% off equal to 30% off?
Usually no. Applied sequentially, the second discount is taken from the already reduced price, giving 28% effective savings.
How do I find the original price from a sale price?
Divide the sale price by one minus the discount rate, assuming there were no other discounts or fees.
Does discount come before sales tax?
Often, but tax treatment varies by jurisdiction and coupon type. Use the checkout rules that apply to the transaction.
What should I verify about separate coupons from percentage discounts?
A fixed-amount coupon usually reduces the post-discount price, but retailer terms, minimum spend and tax calculations can affect ordering. Verify what the offer actually applies to.