Discount Calculator

How to use the discount calculator

1. Pick a mode: price after a percentage off, two stacked discounts, the original price behind a sale price, or the percentage off between two prices.
2. Enter the numbers the mode asks for — an original price, a sale price, or both.
3. Tap a quick pick (10%, 20%, 25%, 30%, 50%, 70%) or type any discount you like.
4. Add a sales tax or VAT rate if you want the amount you will actually pay at the till. Leave it at 0 for a tax-free or tax-inclusive price.
5. Read the results and the comparison table, which shows what every common percentage would cost on the same item.

Results update as you type, and nothing you enter leaves your browser.

How it works

Each mode is one line of arithmetic.

Tax is applied last, to the discounted price:

tax   = discounted price × tax rate / 100
total = discounted price + tax

That order matters. On a $200 coat at 50% off with 20% VAT, you pay tax on $100, not on $200 — the discount saves you $20 of tax on top of the $100 off the price.

Why stacked discounts are smaller than they look

The single most common mistake in a sale is adding two percentages together. A sign reading “30% off, take a further 20% off at the register” is not 50% off. The second discount applies to the already-reduced price:

$100 × 0.70 = $70      (after 30% off)
$70  × 0.80 = $56      (after a further 20% off)
saved = $44, which is 44% off, not 50%

The shortfall grows with the size of the discounts. Two 50% discounts give 75% off, not 100% — you can stack percentage discounts forever and never reach free.

Worked examples

A single discount. A $79.99 jacket at 30% off costs $55.99 and saves $24.00. Add 8.25% sales tax and you hand over $60.61.

Stacked offers. A $100 pair of boots at 30% off with an extra 20% at the checkout costs $56.00. The total discount is 44%, six points less than the 50% the signs imply, and $6 more than you might have budgeted.

Working backwards. A lamp is marked $56 “after 30% off”. Its original price was $80, so the saving really is $24 — useful for checking whether the “was” price on the tag is plausible.

Reading a sale tag. A shirt reduced from $59.99 to $34.99 is 41.7% off, saving $25.00. Shops often round this up to “up to 45% off” in their advertising.

Tax on the discounted price. A $200 coat at 50% off is $100, and 20% VAT adds $20 for a total of $120. Without the discount you would have paid $240 — the saving is $120, not $100.

Tips and common mistakes

• Never add stacked percentages. Multiply the remaining fractions instead, or let the stacked mode do it.
• Check the “was” price. Use the reverse mode: if a “60% off” tag implies an original price nobody ever paid, the discount is smaller than advertised.
• Percentage off is not percentage saved on your budget. A 70% discount on something you did not need still costs 30% of the price.
• Compare the final price, not the discount. Two shops with different starting prices can advertise very different percentages and end up within a dollar of each other.
• Watch for a discount applied before a delivery fee. Shipping and handling are usually added after the discount and sometimes after tax.
• Coupons that give a fixed amount off behave differently from percentage coupons: on a cheap item a flat $20 coupon can beat 30% off, and on an expensive one it will not.

The figures here are estimates for comparing offers. Shop rounding rules, regional tax rates and exclusions written into the small print can move the amount you actually pay at the till.

Glossary

• List price – the original, undiscounted price of an item.
• Sale price – the price after the discount has been applied.
• Stacked discount – a second discount applied to an already-reduced price.
• Effective discount – the total saving expressed as a percentage of the original price.
• VAT – value added tax, included in the shelf price in many countries; US sales tax is added at the register instead.

Last reviewed: September 21, 2026