Percentage toolkit
Calculate a percentage, compare two numbers, or increase and decrease an amount.
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Discount & sales tax calculator
A sale, minus the mental gymnastics.
Your numbers
Stack two discounts, add a tax rate, and see the final price and actual saving.
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THE MATH, WITHOUT THE MYSTERY
What’s actually happening here?
Successive discounts multiply; they do not add. A 20% discount followed by another 10% is an effective 28% discount, not 30%.
The entered tax is added after both discounts. Savings compare the final price with the original price plus that same tax rate, so the comparison is like-for-like.
THE FORMULA
Final price = Original × (1 − d₁) × (1 − d₂) × (1 + tax)
A small example
An original price of 100 with 20% off, then 10% off, becomes 72 before tax. Adding 5% tax makes the final price 75.60.
GOOD QUESTIONS
A few things worth knowing.
Can I enter a price that already includes tax?
For a simple discount-only calculation, enter the tax-inclusive price and set added tax to 0%. The separate tax breakdown then does not apply.
Why do the discounts not add up?
The second percentage applies to a smaller amount. Taking 10% off 80 saves 8, not 10.