Discount Calculator
Calculate sale prices, stack multiple discounts correctly (20% + 10% is not 30% off), add sales tax, or find the original price from a sale price. Free, instant, any currency.
Why 20% + 10% Doesn't Equal 30% Off
This is genuinely one of the most common pricing misconceptions. When discounts stack, each one applies to the already-reduced price, not the original — so combined discounts are always less than simply adding the percentages together.
Common Discount Calculation Mistakes
| Mistake | Correct Approach |
|---|---|
| Adding stacked percentages directly | Apply each discount sequentially to the reduced price |
| Applying tax before the discount | Tax is applied to the final discounted price in standard retail |
| Confusing "% off" with "% of" | 25% off $80 means you pay $60, not that the discount equals $20 alone as the price |
| Assuming BOGO 50% = 50% off everything | "Buy one get one 50% off" is actually 25% off per item across the pair |
How Sales Tax Interacts With Discounts
In standard retail practice, sales tax is calculated on the final discounted price, not the original price. Applying tax before the discount would overcharge — always discount first, then apply tax to what's left. This calculator handles that order automatically when you enable the tax option.
Three Ways to Use This Calculator
- Find Sale Price. Enter the original price and one or more stacked discounts to see the final price and total savings.
- Find Discount %. Know both the original and sale price but want to confirm the actual percentage off? This mode calculates it directly.
- Find Original Price. Working backward from a sale price and known discount percentage to figure out what the item cost before the markdown.
Comparing Deals Effectively
When comparing multiple offers, always compare the effective discount percentage and final total (including tax), not just the headline percentage advertised — a "30% off" sign paired with a smaller stacked coupon might genuinely save less than a straightforward 28% single discount elsewhere. If you're pricing your own products rather than shopping, our Profit Margin Calculator can help ensure a discount doesn't erode your margin below a safe threshold.
FAQs
Why doesn't 20% + 10% equal 30% off?
Because stacked discounts apply sequentially — the second discount reduces the already-discounted price, not the original. 20% then 10% off equals 28% total, not 30%.
How many discounts can I stack?
Up to 3 sequential discounts in this calculator, applied in the order you enter them.
Should tax be calculated before or after the discount?
After — standard retail practice applies sales tax to the final discounted price, not the original price. This calculator handles that order automatically.
How do I find the original price from a sale price?
Use Find Original Price mode — enter the sale price and the discount percentage that was applied, and it calculates what the item cost before the markdown.
What does "effective discount" mean?
It’s your total savings as a single percentage of the original price — useful for comparing deals with different numbers of stacked discounts on an apples-to-apples basis.
Is "Buy One Get One 50% Off" the same as 50% off everything?
No — it’s actually 25% off per item across the pair, since only one of the two items gets the discount.
Can I use this to check if a deal is genuinely good?
Yes — the AI Deal Checker can give context on whether your specific discount represents good value once you’ve calculated it.
Is this calculator free?
Yes, completely free with no sign-up required.