utility

How to Calculate Discounts and Final Prices

How discounts change a list price, including stacked offers, tax and the effective savings percentage.

Published October 18, 2026

How to Calculate Discounts and Final Prices

How discounts change a list price, including stacked offers, tax and the effective savings percentage. Use the free RapidCalc calculator to check your own numbers and explore different inputs.

The basic discount formula

Sale price = original price × (1 − discount rate ÷ 100). A $150 item at 20% off costs $120 before any additional tax or fees. Savings are $30.

Two discounts are not additive

With two successive discounts, multiply both remaining-price factors. A $100 item discounted by 20% and then another 20% costs $64—not $60. The effective discount is 36%.

Adding sales tax after discounts

If sales tax is 8% on a discounted $64 item, tax is $5.12 and checkout total is $69.12. Rules about taxable discounts can vary by jurisdiction.

Compare offers fairly

Compare the final payable amount, not only the advertised percent. A coupon may exclude certain products, limit stacking, or apply before shipping.

Common mistakes

Do not add sequential discounts, confuse dollars saved with percent saved, or assume tax applies identically everywhere.

Try your own example

Open the interactive calculator and change one number at a time to see the effect. Read the assumptions attached to the result before applying it to a real transaction.

Educational information only; product rules, tax rates and financial terms vary.

← Browse all guides