Discount Calculator Calculators
Work out a sale price, the saving, and stacked discounts.
Discount Calculator is a free online tool that work out a sale price, the saving, and stacked discounts. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free — no account, no quota, no watermark
- Category
- Calculators
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- 5
- Works offline
- Yes, after the first visit
About Discount Calculator
Stacked discounts multiply rather than add, which is where "50% off plus an extra 20%" comes unstuck — that is 60% off, not 70%. The tool applies the second discount to the already-reduced price and shows the true effective rate, which is usually lower than the advertising implies.
How to use it
- Enter original price, discount and extra discount at checkout.
- Adjust the remaining 2 settings if the defaults do not fit your case.
The 5 settings
| Setting | What it does | Default |
|---|---|---|
| Original price | A numeric value. | 120 |
| Discount | Range 0–100%. | 25% |
| Extra discount at checkout | Range 0–100%. | 0% |
| Tax added after | A numeric value. | 0% |
| Currency | Choose from 7: USD $, GBP £, EUR €, INR ₹, AUD A$, CAD C$…. | USD $ |
Under the hood
| Runs on | plain JavaScript — runs the whole thing |
| Controls | Original price, Discount, Extra discount at checkout, Tax added after, Currency |
Questions
Why is 30% off plus 20% off not 50% off?
The second discount applies to the reduced price. $100 → $70 → $56, which is 44% off in total. Retailers know this; the phrasing is deliberate.
What does the currency option change?
It offers 7 choices — USD $, GBP £, EUR € and INR ₹ and more. The default is USD $, which suits most cases; change it when your input or your destination calls for something specific.
What are the limits on discount?
It accepts 0 to 100%, starting at 25%. The other numeric controls have their own ranges: extra discount at checkout 0–100%.
Is the arithmetic exact?
It uses double-precision floating point — about 15 significant figures, far more than the inputs justify. Displayed rounding is cosmetic; the underlying numbers are not rounded between steps, so chained results do not drift.