Discount Calculator

How this discount calculator works

Enter the original price and discount percentage to see exactly how much you save and your final price. It also supports a second stacked discount and sales tax, since real-world purchases often involve more than a single flat percentage off.

The discount formula

Sale Price = Original Price × (1 − Discount% ÷ 100)

For a second stacked discount, apply the same formula again to the already-discounted price, not to the original price.

Step-by-step: how to calculate a discount

Convert the discount percentage to a decimal (25% becomes 0.25).
Multiply the original price by (1 minus that decimal) to get the discounted price.
If there’s a second discount, repeat the calculation using the new discounted price, not the original.
If tax applies, multiply the final discounted price by (1 plus the tax rate as a decimal).

Worked example

An $80 item with a 25% discount, an additional 10% stacked discount, and 8% sales tax:

After 25% off: $80 × 0.75 = $60.00
After additional 10% off: $60 × 0.90 = $54.00
Total saved before tax: $80 − $54 = $26.00
Final price with 8% tax: $54 × 1.08 = $58.32

Notice the two discounts don’t simply add to 35% off, stacking 25% and 10% actually saves 32.5% off the original price ($26 off $80), not 35%, because the second discount applies to an already-reduced price.

Common mistakes

Adding stacked discount percentages together instead of applying them sequentially, which overstates your real savings.
Calculating tax before the discount instead of after, which usually isn’t how in-store pricing works.
Forgetting that percentage off and dollar amount off require different formulas, don’t mix them up when comparing deals.

Tips for spotting the better deal

Always calculate the actual final price rather than trusting the advertised percentage alone.
When comparing two different stores’ discounts on the same item, run both through the same calculation to compare apples to apples.
Watch for stores applying tax before rather than after a discount, it changes the final price slightly.

Do two stacked discounts add together?

No. A 25% discount followed by a 10% discount doesn’t equal 35% off, it equals 32.5% off, because the second discount is applied to the already-reduced price, not the original.

Should sales tax be calculated before or after a discount?

Almost always after, most retailers apply sales tax to the final discounted price, not the original price.

How do I compare a percentage discount to a flat dollar-amount discount?

Convert both to a final price using the same original price, then compare which results in the lower final cost, percentages and flat amounts aren’t directly comparable without doing this conversion.

What’s the fastest way to estimate a 25% discount?

Divide the price by 4, that’s exactly 25% and gives you the amount saved instantly. Subtract it from the original price for the final cost.