Discount Calculator

Features

• Sale price, savings and effective discount
• Stacked discounts calculated correctly
• Reverse calculation to find the original price
• Optional tax applied after the discount
• Step-by-step breakdown of every calculation

How to use it

1. Pick which calculation you need.
2. Enter the price and discount percentages.
3. Read the final price and savings.
4. Check the breakdown to see the working.

Why stacked discounts never add up

A 20% discount followed by another 20% is not 40% off. The second discount applies to the already-reduced price, so you pay 80% of 80%, which is 64% of the original, an effective discount of 36%, not 40%. The gap widens as the discounts grow: two 50% discounts leave you at 25% of the original rather than free.

The order does not matter mathematically, multiplication is commutative, so 20% then 10% gives the same result as 10% then 20%. It can matter legally and practically, though. Some retailers apply percentage discounts before fixed-amount vouchers, others after, and the difference is real money. Tax is normally calculated on the discounted price, which is what this tool does.

The pricing tactic worth being aware of is the reference price. A discount is only meaningful relative to a price the item actually sold at, and “was £200, now £100” tells you nothing if it never sold at £200. Several jurisdictions regulate this, EU rules require the displayed prior price to be the lowest price charged in the preceding 30 days, and similar rules exist in the UK and Australia. Comparing against what competitors charge is a better guide than the percentage on the label.