折扣计算器 — 折扣比例、优惠价格与节省金额
本折扣计算器即时计算应用百分比或固定折扣后的优惠价格和节省金额。输入原价和折扣，查看最终费用、总节省金额以及含税后的单价。
Calculate Your Discount
Enter the original price and discount percentage to see how much you save.
常见问题
折扣计算器是如何工作的？
折扣计算器用原价乘以折扣百分比，得出节省金额，然后用原价减去节省金额得出折后价。公式为：折后价 = 原价 × (1 - 折扣率/100)。
如何计算多重折扣？
多重折扣需要依次计算。例如，先打 20% 折扣，再打 10% 折扣，等效折扣不是 30%，而是 1 - (0.8 × 0.9) = 28%。本计算器支持连续折扣计算。
折扣与降价有什么区别？
折扣通常是临时性的价格优惠，以百分比表示（如 8 折）；降价是对原始定价的永久性调整。两者都可用本计算器计算节省金额。
如何计算折扣百分比？
折扣百分比 = (原价 - 折后价) / 原价 × 100。例如，原价 $100，折后价 $75，则折扣率 = (100 - 75) / 100 × 100 = 25%。
How to Calculate Discounts and Sale Prices
Discount Formulas
Percent Off (Sale Price):
Discount Amount = Original Price x (Discount % / 100)
Sale Price = Original Price - Discount Amount
Sale Price = Original Price x (1 - Discount % / 100)
Example: 25% off a $80 jacket: $80 x (1 - 0.25) = $80 x 0.75 = $60 sale price. You save $20.
Find Original Price Before Discount:
Original Price = Sale Price / (1 - Discount % / 100)
Example: You paid $60 after a 25% discount: $60 / (1 - 0.25) = $60 / 0.75 = $80 original price.
Stacked (Double) Discounts:
Effective Multiplier = (1 - Discount1 / 100) x (1 - Discount2 / 100)
Final Price = Original Price x Effective Multiplier
Effective Discount % = (1 - Effective Multiplier) x 100
Example: 20% off then 10% off a $100 item: (0.80 x 0.90) = 0.72, so $100 x 0.72 = $72 final price (28% effective discount, not 30%).
Step-by-Step Examples
Example 1: 25% Off an $80 Item
- Original price: $80.00
- Discount rate: 25%
- Discount amount: $80.00 x 0.25 = $20.00
- Sale price: $80.00 - $20.00 = $60.00
You save $20.00 (25% off) — final price $60.00
Example 2: Stacking 20% Then 10% Off a $100 Item
- Original price: $100.00
- First discount (20%): $100.00 x 0.80 = $80.00
- Second discount (10%): $80.00 x 0.90 = $72.00
- Total savings: $100.00 - $72.00 = $28.00
- Effective discount: 28% (not 30%)
Stacked 20% + 10% = 28% effective discount — final price $72.00
Example 3: Finding the Original Price from a Sale Price
- Sale price: $60.00
- Discount was: 25%
- Multiplier: 1 - 0.25 = 0.75
- Original price: $60.00 / 0.75 = $80.00
The item originally cost $80.00 before the 25% discount
Quick Discount Reference Table
Sale prices for common original prices and discount rates:
| Original | 10% | 15% | 20% | 25% | 30% | 40% | 50% |
|---|---|---|---|---|---|---|---|
| $25 | $22.50 | $21.25 | $20.00 | $18.75 | $17.50 | $15.00 | $12.50 |
| $50 | $45.00 | $42.50 | $40.00 | $37.50 | $35.00 | $30.00 | $25.00 |
| $75 | $67.50 | $63.75 | $60.00 | $56.25 | $52.50 | $45.00 | $37.50 |
| $100 | $90.00 | $85.00 | $80.00 | $75.00 | $70.00 | $60.00 | $50.00 |
| $150 | $135.00 | $127.50 | $120.00 | $112.50 | $105.00 | $90.00 | $75.00 |
| $200 | $180.00 | $170.00 | $160.00 | $150.00 | $140.00 | $120.00 | $100.00 |
Smart Shopping Tips
Is a Bigger First Discount Better?
When stacking two discounts, the order does not matter mathematically. 20% off then 10% off gives the exact same result as 10% off then 20% off. The multiplication is commutative: 0.80 x 0.90 = 0.90 x 0.80 = 0.72. What matters is the total effective discount, which is always less than the sum of the individual percentages.
Percent Off vs. Dollar Off: Which Saves More?
It depends on the item price. A $10 off coupon is better than 10% off on items under $100, but worse on items over $100. The breakeven point is: Breakeven Price = Dollar Off / (Percent Off / 100). For example, $15 off vs. 20% off: $15 / 0.20 = $75. Below $75, take the $15 off. Above $75, take the 20% off.
How to Spot Fake Discounts
Retailers sometimes inflate the "original" price to make discounts look larger. Watch for these warning signs:
- The item is always "on sale" and never sold at the listed original price
- The original price is much higher than the same product at competing retailers
- Discounts over 50% on non-clearance or non-seasonal items
- No price history available (use browser extensions like CamelCamelCamel or Honey to track prices)
- Compare prices across at least 2-3 retailers before trusting a "deal"