Máy tính giảm giá
The detailed guide below is currently available in English.
Why stacked discounts do not add up
A second percentage applies to the already-reduced price, so 20% off followed by 10% off is 0.8 × 0.9 = 72% of the original — a 28% total discount, not 30%. Retailers count on the difference, so it pays to convert stacked offers into one effective percentage before deciding whether a deal is good.
Judging a discount
A large percentage off a small base can save less than a modest cut on a big-ticket item — compare the dollar "You save" figure, not just the percentage. Also check whether the "original price" is genuinely the street price; the math here is exact, but it is only as honest as the starting price you enter.
Câu hỏi thường gặp
How do I calculate 20% off a price?
Multiply the price by 0.8. The calculator shows the same result plus the dollar amount saved — enter 20 in the first discount field.
What does "20% + extra 10% off" really give me?
It compounds to a 28% discount, because the extra 10% comes off the discounted price. Enter both discounts to see the true final price and effective rate.