Discount Calculator
Calculate discounted price, savings, tax, and quantity total
Discount Calculator — what it does
Enter an original unit price, a discount rate, a tax rate and a quantity, and the calculator returns the discounted unit price, the total saved, the tax due and the final amount payable. Having all four figures at once answers both questions a discount raises: what does one cost now, and what does the whole purchase actually come to?
When this tool helps
- Checking what a sale price really comes to at the till once tax is added back on top.
- Comparing offers stated differently — 20 percent off one brand against a lower list price on another.
- Quoting a client a volume discount and stating the tax-inclusive total in the same breath.
How to use it
- Enter the original unit price.
- Set the discount rate and the tax rate.
- Enter the quantity.
- Calculate to see unit price, savings, tax and total payment.
Accuracy, limits, and good practice
- Tax is applied to the discounted amount, which matches how retail systems almost universally calculate it.
- Two successive discounts do not add: 20 percent off then 10 percent off is 28 percent off, not 30.
- For comparing package sizes rather than discounts, price per unit is the honest measure — the unit price comparison tool does that.
Frequently asked questions
How do I reverse a discount?
Divide the sale price by one minus the rate. Something sold at 80 after 20 percent off started at 100.
Does the order of discount and tax matter?
Yes, and discount-then-tax is the standard. Applying tax first and discounting after gives the customer slightly less benefit.
Can I use this for a marked-up price instead?
Enter a negative discount rate and the tool effectively applies a surcharge, though a margin calculator suits pricing work better.
Related tools on this site
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- Compound Interest Calculator — Estimate future value with compounding and regular contributions
Everything above runs inside this page. Discount Calculator needs no account, no upload, and no server round trip — close the tab and nothing is left behind.
折扣計算器能做什麼
輸入原始單價、折扣率、稅率與數量，計算器會回傳折後單價、共省下多少、應繳稅額與最終付款總額。四個數字同時到位，正好回答折扣引出的兩個問題：現在一件多少錢？整筆買下來實際付多少？
什麼時候用得上
- 確認特價商品加回稅後，結帳時實際是多少錢。
- 比較不同表述的優惠：一邊打八折，另一邊直接標低價。
- 向客戶報數量折扣時，同時講清楚含稅總額。
使用步驟
- 輸入原始單價。
- 設定折扣率與稅率。
- 輸入數量。
- 計算後查看折後單價、省下金額、稅額與總付款。
精確度、限制與實務建議
- 稅是以折後金額計算，與零售系統幾乎一致的算法相同。
- 連續折扣不能相加：先八折再九折是七二折，不是七折。
- 比較不同包裝容量時，每單位價格才是誠實的指標，可用單位價格比較工具。
常見問題
怎麼反推折扣前的價格？
把成交價除以（1 − 折扣率）。打八折後賣 80 的商品，原價就是 100。
先折扣還是先加稅有差嗎？
有，而且「先折扣、後計稅」是標準做法；反過來算，客戶得到的優惠會略少。
可以拿來算加價嗎？
把折扣率填負數即等於加收費用，不過訂價工作用利潤率計算器更合適。
本站相關工具
以上步驟全部在這個頁面內完成，折扣計算器 不需要註冊、不上傳檔案、也不經過伺服器，關閉分頁後不會留下任何資料。