Free Discount & Sale Price Calculator

How It Works

All calculation happens directly in the browser using plain JavaScript arithmetic — no library, no server request. Locale-aware currency formatting is handled by the browser's built-in Intl.NumberFormat API, which correctly places symbols, separators, and decimal places for any locale and currency you select.

1. 1
   Choose a calculation mode

   Three modes cover the common retail scenarios: apply a known percentage off to a price, work backwards from original and sale price to find the discount percentage, or find how much you saved. Switching modes changes which inputs are shown.
2. 2
   Arithmetic runs on every keystroke

   For 'apply discount' and 'savings' modes, the final price is computed as original × (1 − d₁/100) × (1 − d₂/100), which correctly models two stacked discounts as multiplicative — not additive. For 'calculate' mode, the percentage is (original − final) / original × 100. An optional sales-tax field multiplies the post-discount price by (1 + tax/100).
3. 3
   Intl.NumberFormat formats the result

   The browser's built-in Intl.NumberFormat API renders every currency amount — placing the symbol correctly for USD, EUR, JPY, INR, and the other supported currencies, and applying zero decimal places for JPY automatically based on locale data the browser already has.
4. 4
   Deal comparison finds the better unit price

   The optional deal-comparison panel computes a per-unit cost for each deal as (price × (1 − discount/100)) / quantity, then highlights whichever is lower and shows the per-unit difference.

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