Enter a price and discounts to get the final price and your savings
Enter a valid price (0.01-1,000,000)
Enter a valid discount (0-100)
Enter a valid discount (0-100)
Enter a valid tax rate (0-100)
Discounts look simple until a second one is stacked on top or tax is added at the till. "Take 20% off, then an extra 10%" does not mean 30% off, and tax is usually charged on the reduced price rather than the original. This calculator combines an original price, one or more discounts and an optional tax rate so you can see the true final cost and the real saving.
Each discount is applied to the running price, so the second discount is smaller in cash terms than the first. The rate d is written as a decimal (20% = 0.20).
The combined discount is not d₁ + d₂ but 1 − (1 − d₁)(1 − d₂). Two successive 20% discounts leave 0.8 × 0.8 = 0.64, an effective 36% off. Tax normally attaches to the discounted subtotal, so it should be added last, on the reduced price, not on the original.
A $99 jacket has 20% off, an extra 10% coupon and 8% sales tax. After the first discount the price is 99 × 0.8 = $79.20. The extra coupon gives 79.20 × 0.9 = $71.28. Tax then adds 71.28 × 1.08 = $76.98. The total discount is 1 − (0.8 × 0.9) = 28%, and the cash saving is 99 − 71.28 = $22.02.
| Step | Calculation | Value |
|---|---|---|
| After 20% off | 99 × 0.80 | $79.20 |
| After extra 10% | 79.20 × 0.90 | $71.28 |
| With 8% tax | 71.28 × 1.08 | $76.98 |
| Total saving | 99 − 71.28 | $22.02 |
Always confirm the order of operations: when a store applies tax before a discount, the final price is slightly higher. Do not add stacked percentages together, and remember that "save 28%" refers to the pre-tax saving while the checkout total includes tax. To reverse-engineer an original price from a discounted one, divide by (1 − discount) instead of subtracting.
折扣看似简单，可一旦叠加第二重折扣、或在收银台加税就容易出错。"先打八折，再额外九折"并不等于七折，而税通常按折后价格而非原价计征。本计算器可处理原价、一重或多重折扣以及可选的税率，帮你算出真正的最终价格与实际节省金额。
每一重折扣都作用在当时的现价上，因此第二重折扣在金额上比第一重更少。折扣率 d 以小数表示（20% = 0.20）。
叠加后的折扣不是 d₁ + d₂，而是 1 − (1 − d₁)(1 − d₂)。连续两次八折后剩下 0.8 × 0.8 = 0.64，相当于实际省下 36%。税一般按折后小计计征，所以应最后再乘到折后价上，而不是加在原价上。因此当促销写着"最高省 X%"时，通常指的是单重折扣，多张券叠加后需要按乘法重新计算实际折扣。
一件 99 美元的外套先打八折，再叠加一张九折券，另收 8% 销售税。第一次折扣后：99 × 0.8 = 79.20 美元；九折券后：79.20 × 0.9 = 71.28 美元；加税后：71.28 × 1.08 = 76.98 美元。总折扣为 1 − (0.8 × 0.9) = 28%，实际省下 99 − 71.28 = 22.02 美元。
| 步骤 | 计算 | 数值 |
|---|---|---|
| 打完八折 | 99 × 0.80 | $79.20 |
| 再打九折 | 79.20 × 0.90 | $71.28 |
| 加 8% 税 | 71.28 × 1.08 | $76.98 |
| 总共节省 | 99 − 71.28 | $22.02 |
务必确认运算顺序：如果商家先加税再打折，最终价格会略高。不要直接把叠加的百分比相加，同时要记住"省 28%"指的是税前节省，而结账总额已含税。若要从折后价反推原价，应当除以 (1 − 折扣率)，而不是用减法。另外，"第二件半价""满减""买一送一"等促销的等价折扣率各不相同，最好先换算出实际折扣率，再套用本工具进行比较。
Multiply the original price by (1 − discount%). A 20% discount on $99 gives 99 × 0.8 = $79.20.
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 in total, not 30%.
In most regions tax is charged on the discounted (net) price. Enter the tax rate here and the calculator adds it after the discount.