Savings and discounted price
savings = original × d/100; discounted = original − savings- d = discount rate from 0 to 100
A 100% discount produces a discounted price of zero.
Discount calculator
Use the Discount calculator for fast, clear results with formulas and practical examples.
Discount calculator
Result90
Savings30Tax0
What this calculator answers
Use this calculator to check a single percentage discount and an optional percentage tax. It does not combine stacked discounts, coupons with special conditions, shipping, or fixed fees.
Input definitions
- Original price
- The non-negative price before the percentage discount.
- Discount
- A rate from 0% to 100%; enter 25 for a 25% reduction.
- Tax
- An optional non-negative rate applied to the discounted price, not to the original price.
Formulas and variables
Tax and final price
tax = discounted × t/100; final = discounted + tax- t = entered tax rate
Actual taxable bases and rounding law vary; this is a mathematical estimate using the discounted price.
Assumptions and rounding
- Exactly one discount rate and one tax rate are applied in that order.
- Currency is not converted; outputs use the same currency as the original price.
- Full precision is retained until display. Money examples round the final values to two decimals.
- Jurisdiction-specific tax exemptions, compound taxes, fees, and merchant rounding rules are outside scope.
Worked examples
25% discount followed by 8% tax
Original price 120.00, discount 25%, tax 8%.
Calculation- Savings: 120.00 × 0.25 = 30.00.
- Discounted price: 120.00 − 30.00 = 90.00.
- Tax: 90.00 × 0.08 = 7.20.
- Final price: 90.00 + 7.20 = 97.20.
Result: Save 30.00 and pay an estimated 97.20.
15% discount with no tax
Original price 49.99, discount 15%, tax 0%.
Calculation- Savings: 49.99 × 0.15 = 7.4985.
- Discounted price: 49.99 − 7.4985 = 42.4915.
- Round the displayed monetary result once: 42.49.
Result: Displayed savings 7.50; displayed final price 42.49.
Questions people ask
- Is tax calculated before or after the discount?
- This calculator applies tax after the discount. Check local rules and the merchant invoice because the legal taxable base can differ.
- How do I handle two successive discounts?
- Apply them sequentially, not by adding the percentages. A 20% discount then 10% off leaves 0.8 × 0.9 = 72% of the original price, a 28% total reduction.
- Why is the exact savings more than two decimal places?
- Percentage multiplication can create fractions of the smallest currency unit. The engine retains them and the display rounds at the end.
- Does this include shipping or fixed coupons?
- No. Add or subtract fixed amounts separately and follow the merchant’s stated order of operations.
Boundaries and common mistakes
- Do not add stacked discount percentages unless they share the same original base.
- Do not assume every jurisdiction taxes the discounted price in exactly this way.
- Avoid rounding the savings before calculating tax unless the applicable invoice rule requires it.
Sources and scope
- OpenStax Prealgebra 2e — Understand PercentApplies to: Percent as a ratio per hundred and the arithmetic used by percentage, tip, and discount calculations.
Variables, defaults, and limits
- Original price
- Original price is a number input. The displayed starter value is 120; it is an example, not a hidden assumption.
- Default: 120
- Accepted values: Minimum: 0. Numeric entries must be finite and unambiguous.
- Discount
- Discount is a number input. The displayed starter value is 25; it is an example, not a hidden assumption.
- Default: 25
- Accepted values: Allowed range: 0 to 100. Numeric entries must be finite and unambiguous.
- Tax
- Tax is a number input. The displayed starter value is 0; it is an example, not a hidden assumption.
- Default: 0
- Accepted values: Minimum: 0. Numeric entries must be finite and unambiguous.
Worked examples
Discount calculator evaluated example 1
Use the page’s labelled starter inputs to verify Discount calculator.
Inputs- Original price: 120
- Discount: 25
- Tax: 0
Evaluated result: 90
Discount calculator evaluated example 2
Enter price = 249.99, discount = 18.5, and tax = 7.2 for an item taxed after the markdown.
Inputs- Original price: 249.99
- Discount: 18.5
- Tax: 7.2
Evaluated result: 218.41
Validation and boundaries
- Every visible required input must be present; a missing value is never replaced with zero.
- NaN, positive or negative infinity, unsafe overflow, and a non-finite final result are rejected.
- Field-specific minimums, maximums, and choices apply to Original price, Discount, Tax.
- Zero, negative values, and discrete counts are accepted only when the displayed field definition permits them.
Review and correction links
Frequently asked questions
- Can I subtract an 8% tax rate from a 20% discount and call the net discount 12%?
- No. The percentages use different bases: multiplying by 0.80 and then 1.08 leaves 86.4% of the original price, a 13.6% reduction.
- What question does Discount calculator answer?
- Use the Discount calculator for fast, clear results with formulas and practical examples. The implemented relationship is S=x₁·(1−x₂/100); R=S·(1+x₃/100); x₁=Original price; x₂=Discount; x₃=Tax.
- Which inputs does Discount calculator use?
- It uses the visible fields Original price, Discount, Tax. No hidden value is substituted for an omitted required input.
- What happens when Discount calculator receives an invalid or extreme value?
- The page rejects missing, ambiguous, out-of-range, or non-finite values and refuses to display a non-finite result.
- Why can Discount calculator differ from another result?
- Different unit conventions, endpoint policies, fee or rate assumptions, formula domains, and premature rounding can produce a different answer.
- Can I use Discount calculator as professional advice?
- No. It answers the displayed mathematical question and cannot account for omitted real-world facts.
- How can I verify the Discount calculator result?
- Recalculate the two evaluated examples without rounding intermediate values and compare the declared formula or convention with Standard percentage arithmetic.
Source and review scope
Standard percentage arithmetic
Scope: Standard percentage arithmetic is used to check the formula, definition, or convention relevant to Discount calculator. The citation does not supply current personal, lender, tax, medical, or market data.
Source checked: