Discount Calculator

Calculate final retail prices with stacked discounts, flat savings, and sales tax.

Calculation Mode

Deal Settings

Original Price ($)

Discount Type

Discount Rate (%)

Stacked Extra Discount (% off)

Sales Tax (%)

Discount Presets Reference Table (Original Price: $80.00)

Discount	You Save	Sale Price
5% off	$4.00	$76.00
10% off	$8.00	$72.00
15% off	$12.00	$68.00
20% off	$16.00	$64.00
25% off	$20.00	$60.00
30% off	$24.00	$56.00
40% off	$32.00	$48.00
50% off	$40.00	$40.00
60% off	$48.00	$32.00
70% off	$56.00	$24.00

Total Checkout Price

$58.32

Subtotal:$54.00

Sales Tax:$4.32

Total Savings:$26.00

Stacked Discount Note: Double discounts are applied sequentially. The first discount is subtracted from the original price, and then the second discount is calculated from that intermediate subtotal. This is not the same as a single combined discount.

How stacked discounts and sales tax are calculated

Sequential discounts (e.g. 20% off plus an extra 10% coupon) are calculated by multiplying discount factors:Price after discounts = Original Price × (1 - D1/100) × (1 - D2/100). Flat discounts are subtracted directly from the initial price before secondary percentage discounts are applied.

Sales tax is added as a percentage of the final discounted subtotal: Tax = Subtotal × Tax Rate / 100. Use the reverse mode to determine the discount percentage of any marked-down price.

Built and maintained by Meet Shah · Last updated 1 August 2026

What this tool is used for

Working out a sale price from a percentage off.
Finding the saving in money rather than as a percentage.
Working backwards from a sale price to the discount applied.
Comparing two offers expressed differently.
Checking a till price against the advertised discount.

Frequently Asked Questions

Why do stacked discounts not add up?: Because each applies to the running total. 20% then 10% is 0.8 × 0.9 = 0.72, a 28% total reduction rather than 30%. The order does not matter to the result, which surprises people who assume the larger one should go first.
How do I reverse a discount?: Divide, do not add back. A price of £80 after 20% off had an original of 80 ÷ 0.8 = £100, not £96. Adding the same percentage to the discounted figure is the single most common error in retail arithmetic.
What does a discount do to margin?: Far more than its size suggests, because it comes entirely out of the margin rather than being shared with the cost. A 10% discount on a product with a 40% margin removes a quarter of the profit; at a 20% margin it halves it.
Is tax applied before or after the discount?: After, in essentially every jurisdiction — you are taxed on what you actually pay. That makes the sequence deterministic, and it is why a receipt showing tax computed on the pre-discount total is an error rather than a policy.
What is the difference between BOGO and a percentage?: Buy-one-get-one-free is a 50% discount on the pair, and buy-one-get-one-half-price is 25% overall — both look larger than they are. Converting an offer to its effective percentage is the fastest way to compare two promotions honestly.

Common errors and gotchas

Applying two discounts additively, when they compound and give a smaller total reduction.
Reversing a discount by adding the same percentage, which never returns the original price.
Applying the discount after tax where the rule is before it, or the reverse.
Comparing a percentage off against a fixed amount off without a price to anchor them.
Rounding the discount rather than the final price, which produces a penny discrepancy.