Tool workspace
Use either percent or amount.
Applied sequentially after the first discount, not added to it.
Optional alternative to percent.
Discount Calculator
Calculate sale price, money saved, and effective discount from an original price and either a percentage or final price. The result keeps currency as an unlabeled numeric amount because tax and currency rules vary.
Browser-localFreeNo upload required
What this tool is for
Calculate sale price, money saved, and effective discount from an original price and either a percentage or final price. The result keeps currency as an unlabeled numeric amount because tax and currency rules vary.
How to use
- Enter the original price.
- Enter the advertised discount percentage or the final sale price.
- Compare savings and final price, then add tax or fees separately if needed.
Example
An original price of 80 with a 25% discount produces 20 saved and a final price of 60 before tax or fees.
FAQ
Does the result include tax?
No. It calculates the stated price relationship only.
Can it stack discounts?
No. Apply sequential discounts explicitly rather than adding their percentages.
Reproducible examples
Known inputs and expected results
Run these examples in the workspace above and compare the result with the documented output.
Percentage discount
- Input
- Original price 100
- Options
- Choose 20% discount.
- Action
- Calculate the sale.
- Expected output
- Savings 20; final price 80.
- Explanation
- The discount is 100 × 0.20 and is subtracted once from the original price.
Fixed-amount discount
- Input
- Original price 80
- Options
- Choose fixed discount 15.
- Action
- Calculate the sale.
- Expected output
- Savings 15; final price 65.
- Explanation
- A fixed amount is subtracted directly and is not interpreted as a percentage.
Error or unsupported case
Discount beyond the price
- Input
- Original price 40; fixed discount 55
- Expected error or limit
- The calculation is rejected with: Discount amount cannot be greater than original price.
- Safer alternative
- Correct the coupon value or model store credit separately.
When not to use this tool
- Stacked coupons, tax, shipping, or tiered promotion engines
- Accounting for refunds, fees, or margin after a discount
Algorithm and assumptions
Percentage savings equal original price × rate/100; fixed savings are subtracted once; currency display rounds only after the underlying calculation.
Input and output
Inputs are non-negative price values and a discount. Output is the saved amount, final price, and effective percentage.
Supported formats and behavior
- Percentage-to-price calculation
- Final-price-to-percentage calculation
- Decimal monetary values
Limits
- No tax, shipping, coupon stacking, or currency conversion
- Rounding follows displayed decimal precision
Edge cases and common errors
- Discounts above 100% are rejected
- A zero original price cannot produce a meaningful percentage
- Negative prices are rejected
Release testing
Checks cover known percentages, reverse calculation, decimals, zero, invalid ranges, reset, and mobile layout.
Privacy boundary
The input and result stay in this browser session. ZZP Box does not upload or store the values entered in this tool.
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