以下のガイドはまだ日本語に翻訳されていないため、英語で表示しています。計算機自体はすべて日本語に対応しています。
この計算機の使い方
- Enter the original price.
- Choose a percentage discount or a fixed amount off, and enter it.
- Optionally add an additional percentage discount applied after the first one.
計算式
Stacked discounts multiply rather than add: 25% off followed by 10% off is 32.5% off in total, not 35%.
Sale price = price × (1 − d₁) × (1 − d₂)
Total discount = 1 − (1 − d₁)(1 − d₂)
Example
- $80 item at 25% off: 80 × 0.75 = $60.
- An extra 10% off: 60 × 0.90 = $54.
- You save $26, which is 32.5% off the original price.
よくある質問
Is 20% + 20% off the same as 40% off?
No. Two successive 20% discounts equal 36% off (1 − 0.8 × 0.8), because the second discount applies to the already-reduced price.
Is sales tax applied before or after the discount?
In most places, tax is calculated on the discounted price. Use the sales tax calculator on the final price.
How do I find the discount percentage from two prices?
Divide the amount saved by the original price. For example, $60 instead of $80 is 20 ÷ 80 = 25% off. The percentage calculator can also do this.