Discount Calculator

How to use the discount calculator

Enter the original price and the discount percentage, and you get what you save and what you’ll actually pay. The defaults — $80.00 at 25% off — save you $20.00 for a $60.00 price. The discount slider runs from 0% to 90%, so you can drag it to match any “% off” tag and watch the final number move. Leave the sales-tax field at 0% and it stays out of the math entirely; fill it in and the tool adds tax to the discounted price, which is exactly how a register rings it up.

A “% off” tag means the percentage comes off the original price, not the price you pay. “25% off” on an $80.00 item is $20.00 off, leaving $60.00 — the discount is always measured against the sticker, never against some already-lowered figure. That distinction matters most the moment a second discount enters the picture, because two percentages don’t simply add together the way the signs make it look.

Stacked discounts are sequential, not additive — each one applies to whatever price is left after the one before it. Take 20% off, then an extra 10% off, on a $100.00 item: the first cut takes you to $80.00, and the extra 10% comes off that $80.00, not the original $100.00, landing you at $72.00. That’s an effective 28% off, not 30%. The second percentage is smaller in dollars because it’s working on a smaller number, so stacked deals always save a little less than the two rates added up would suggest. To check a stacked offer here, run the first discount, then feed the result back in as a new original price with the second rate.

Sales tax goes on last, after the discount, because you’re taxed on what you actually pay — not on the original sticker. So the order is always discount first, then tax on the lower amount. On the $60.00 discounted price, an 8% sales tax adds $4.80 and brings the total to $64.80. Apply tax before the discount and you’d overstate the bill; the discount shrinks the taxable amount, which is one more small reason the savings are worth getting right.

Use the tool to compare offers honestly: a flat “30% off” really is better than “20% then an extra 10%,” even though both sound like the same thirty points. Price each one out, add your local tax rate if you want the out-the-door number, and let the dollars — not the percentage signs — tell you which deal wins.

The formula

A discount is a percentage of the original price taken off; sales tax, if any, is then applied to what’s left:

saved = price × (discount% ÷ 100)
after discount = price − saved
final = after discount × (1 + tax% ÷ 100)

Worked example with the defaults — $80.00 at 25% off: saved = 80 × (25 ÷ 100) = $20.00, so the price after discount is 80 − 20 = $60.00. Add an 8% sales tax and the final is 60 × 1.08 = $64.80. With tax left at 0%, the final is just the discounted price, $60.00; with 0% off, nothing changes and the final stays at the original $80.00.

Note that tax sits on the after-discount line, not the original price — you’re taxed on what you actually pay. And when discounts stack, each rate plugs into “saved” using the price left from the step before, never the original, which is why 20% then 10% off $100.00 lands at $72.00 (an effective 28%), not $70.00.

Frequently asked questions

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