AskANumber.com

Discount Calculator

30% off a $120 item saves $36 and brings the price to $84 — you pay 70% of the original. A percent-off discount multiplies the price by (1 − discount/100): the final price is the fraction of the original you still pay.

Final price
$84.00
You save
$36.00
Original
$120.00
You save $36 at 30% off
30% off means you pay 70% of the original price.
Inputs
% off $
30% off means you pay 70%
You're saving $36.00 and paying 70% of the original. Flipping "percent off" into "percent you pay" is the fastest way to sanity-check whether a sale is as steep as it sounds.
Stacked discounts don't add up
An extra 20% off an already 30%-off price is 44% off, not 50% — the second cut applies to the smaller price. Coupons that stack multiply (0.7 × 0.8), they never simply sum.
Ask a follow-up
Uses your inputs above
$84.00 final price. Want to try a variation?

The math

Reviewed 2026
Formula
final = price · (1 − %/100)

Related calculators

Tip
Sales tax
Percentage

Example: how discount is calculated

Step-by-step with default inputs

Suppose you put the default values into Discount Calculator:

Original price
$120
Discount %
30%

Plug those into the formula final = price · (1 − %/100) and the result is:

Final price
$84.00

How to calculate discount by hand

  1. Convert the discount to a decimal: 30% → 0.30.
  2. Multiply by the price for the saving: $120 × 0.30 = $36.
  3. Subtract from the original price: $120 − $36 = $84 final price.

How does the discount calculator work?

Final price = original × (1 − percent/100), and the saving is original × percent/100 — elementary percentage arithmetic with no external data involved. The two outputs always sum back to the original price, a handy mental check. One subtlety worth knowing: stacked discounts multiply rather than add. A 30% discount followed by an extra 10% off leaves 0.70 × 0.90 = 0.63 of the price — a 37% total discount, not 40% — because the second percentage applies to the already-reduced amount. This calculator applies a single discount; run it twice to chain promotions.

Last reviewed July 2, 2026 · Editorial policy

Frequently asked questions

What is 30% off $120?

$84, a saving of $36. The fastest mental route is the complement: paying after 30% off means paying 70%, and 0.7 × 120 = 84 in one step.

Do discounts of 20% and 10% add up to 30% off?

No — they compound to 28% off. The price becomes 0.80 × 0.90 = 0.72 of the original, because the second discount applies to the already-reduced price rather than the original.

How do I find the original price from a sale price?

Divide by (1 − discount/100): an $84 sale price after 30% off is $84 ÷ 0.70 = $120. Adding 30% back onto $84 gives only $109.20, because the discount was 30% of the larger original.

How accurate is this discount calculator?

The math is deterministic — the same inputs always produce the same output, and the formula is shown above. Accuracy of the answer for your situation depends on how well your inputs match reality and how well the formula models the question.

Why is my bank's number different?

Banks add fees, taxes, insurance, and product-specific terms that this calculator deliberately omits to keep the math transparent. Use this to sanity-check a quote, not to replace it.

How do I share my result?

Hit Share at the top of the page. Every input you change is encoded in the URL, so a permalink reproduces exactly what you see. No account needed.