How to Calculate a Discount and the Final Sale Price
2026-06-03 · 4 min read
A "30% off" sign tells you the discount, not what you pay. Here is how to find the real final price — including tax.
Sales advertise the percentage off, but what you care about is the final price and the amount you actually save. Both are quick to calculate once you know the order of operations.
Step 1: the amount saved
Saved = price × (discount ÷ 100). On a 120 item at 25% off, you save 120 × 0.25 = 30.
Step 2: the discounted price
Subtract the saving from the original: 120 − 30 = 90. You can also do this in one step: price × (1 − discount ÷ 100).
Step 3: add tax (if any)
Tax is applied to the discounted price, not the original. At 10% tax: 90 × 1.10 = 99. Applying tax before the discount would give the wrong total.
Stacked discounts multiply, they do not add. "20% off, then an extra 10% off" is 0.8 × 0.9 = 0.72, i.e. 28% off — not 30%.
Skip the maths
The Discount Calculator shows the final price, the amount saved, and the discounted price before tax, all at once.