Discount Calculator: Easily Calculate Savings, Tax, and Final Price

How to use the tool

• Enter the original price—for example 79.99 or 999.00.
• Add the discount rate %—try 15 or 30.
• Include the sales-tax rate % if relevant—such as 7 or 5.
• Select “Calculate” to display Discount Amount, Price After Discount, Tax Amount and Final Price instantly.

Formulas used

Each result follows straightforward retail math:

• Discount Amount: $$\text{DA}= \text{OP} \times \frac{\text{DR}}{100}$$
• Price After Discount: $$\text{PAD}= \text{OP}-\text{DA}$$
• Tax Amount: $$\text{TA}= \text{PAD} \times \frac{\text{TR}}{100}$$
• Final Price: $$\text{FP}= \text{PAD}+\text{TA}$$

Example 1

• Inputs: OP = $79.99, DR = 15 %, TR = 7 %
• DA: $$79.99 \times rac{15}{100}=12.00$$
• PAD: $$79.99-12.00=67.99$$
• TA: $$67.99 \times rac{7}{100}=4.76$$
• FP: $$67.99+4.76=72.75$$

Example 2

• Inputs: OP = $999.00, DR = 30 %, TR = 5 %
• DA: $$999.00 \times rac{30}{100}=299.70$$
• PAD: $$999.00-299.70=699.30$$
• TA: $$699.30 \times rac{5}{100}=34.97$$
• FP: $$699.30+34.97=734.27$$

Quick Facts

• Average U.S. state sales-tax rate: 5.1 % (Tax Foundation, 2023).
• Holiday promotions deliver mean discounts of 24 % (Adobe Digital Insights, 2022).
• “Discount amount equals original price times rate divided by 100” (Diamond & Pintel, 2016).
• Eight states levy no sales tax (Federation of Tax Administrators, 2023).

FAQ

What is the discount calculator?

The calculator shows how a percentage markdown and optional sales tax affect your final cost, using four simple equations (Diamond & Pintel, 2016).

How does it work?

You enter price and rates; built-in JavaScript multiplies, subtracts and adds to output cent-rounded values that match retail registers (W3 Schools, URL).

Can I leave tax blank?

Yes. A blank or zero tax field skips the third formula, ideal for tax-free jurisdictions (Tax Foundation, 2023).

Why separate discount and tax rates?

Retailers apply tax to the discounted subtotal, not the sticker price, following U.S. state laws (FTA, 2023).

How accurate are the numbers?

The tool uses IEEE-754 double precision and rounds to two decimals, matching card processors’ “round half up” rule (PCI DSS v4.0).

Which currencies are supported?

The default formatter outputs USD, yet you can adapt the code to any ISO 4217 currency symbol (ECMA-402, 2020).

Does the tool store my data?

No personal data is retained; all calculations run client-side and vanish when you reload (MDN Web Docs, URL).

Can I embed it on my site?

Copy the HTML/JS block, adjust styling, and credit the source; the MIT-licensed code allows free reuse (OpenJS Foundation, 2023).