Discount Calculator
Work out the final price and your savings from an original price and discount. Stack a second discount to see the real effective rate.
Stacked discounts multiply. The effective rate is shown too.
How a discount is calculated
The saving equals the original price multiplied by the discount rate, and the final price is the original minus that saving, which is the same as original × (1 − rate). So a $50 item at 20% off saves $50 × 0.20 = $10 and leaves a final price of $50 × 0.80 = $40. The same formula rearranged answers two related questions. To find the discount percentage from two prices, divide the saving by the original: an item cut from $80 to $60 is (80 − 60) / 80 = 25% off. To recover the original price from a sale price, divide by (1 − rate): $63.75 after 15% off was 63.75 / 0.85 = $75 before the sale.
A worked example with a stacked coupon
Suppose a jacket lists at $120, is marked down 30% on the rack, and you also have an extra 15% off coupon that stacks. The rack price is $120 × 0.70 = $84. The coupon then comes off that reduced figure, not the original, so $84 × 0.85 = $71.40. You pay $71.40 and save $48.60. The effective discount is $48.60 / $120 = 40.5% off, noticeably less than the 45% you would get by simply adding 30% and 15%. This gap between the headline rates and the real saving is exactly what trips people up at the register.
Why stacked percentages never simply add
When two percentage discounts stack, you multiply the remaining fractions rather than adding the rates. A 20% discount followed by an extra 10% leaves 0.80 × 0.90 = 0.72 of the price, so the combined effect is 28% off, not 30%. The gap grows with larger numbers: 50% off and then another 50% off is 0.5 × 0.5 = 0.25, a 75% total reduction, and never reaches 100%. A useful side effect is that the order of two percentage discounts does not change the final price, since 20% then 10% and 10% then 20% both land on 0.72 because multiplication is commutative.
Percentage discounts versus fixed-dollar coupons
Order stops being irrelevant the moment a fixed-dollar coupon joins the mix, because a flat amount is not a fraction. Take a $100 item with both a 25% discount and a $10 coupon. Applying the percentage first gives $100 × 0.75 = $75, then − $10 = $65. Applying the $10 first gives $100 − $10 = $90, then × 0.75 = $67.50. The percentage-first path saves you $2.50 more, because the 25% is calculated on the larger $100 base. When you can choose, apply percentage discounts before flat coupons; when the store fixes the order, use this calculator to check which sequence you were actually charged.
Ways to use it
- Shopping preview: before checkout, confirm the sale price and the exact amount you save so a 40% off banner matches the number at the register.
- Coupon stacking: see what a stackable extra 10% really trims once it applies to an already-reduced price rather than the original.
- Comparing offers: put 30% off against $25 off on the same item and compare the two final prices instead of guessing which sounds bigger.
- Receipt check: work backward from what you paid to confirm the advertised discount was actually applied to your order.
Common mistakes to avoid
- Adding stacked percentages: treating 20% plus 10% as 30% off instead of the true 28%.
- Confusing 20% off with 20% of: the first leaves you paying 80% of the price, while 20% of would mean paying only 20%.
- Judging deals by the headline rate: a bigger percentage off a higher sticker price can still cost more than a smaller percentage off a lower one, so compare final prices.
- Forgetting the base: an extra 15% off is 15% of the already-reduced price, not 15% of the original.
- Trusting a markup then a big cut: if a price was inflated before a 50% off sale, the discount may only bring it back to the normal price.
Cautions and limits
- This tool calculates only from the prices you enter and does not add sales tax, VAT, shipping, or handling, which are usually applied after the discount.
- Real coupons often carry conditions such as a minimum spend, a maximum discount cap, category exclusions, or cannot combine with sale items, which a pure calculation cannot know about.
- Up to 70% off describes the best case in a range, not the discount on any particular item.
- For tax on top of a discounted price, pair this with a VAT or GST calculator; for installment or financing offers, a separate loan tool is the better fit.
The amounts you enter are calculated in your browser and never sent to a server.
Read the Privacy Policy →Frequently asked questions
How do I calculate a sale price?
Multiply the original price by (1 − discount rate). A $50 item at 20% off is $50 × 0.80 = $40, saving $10. To go the other way and find the rate from two prices, divide the saving by the original: an item cut from $80 to $60 is 20 / 80 = 25% off.
Is 20% off then 10% off the same as 30% off?
No. The second discount applies to the already-reduced price, so you keep 0.80 × 0.90 = 0.72 of the original, which is 28% off rather than 30%. Stacked percentages always multiply instead of adding, so the true saving is a little smaller than the two rates summed.
Does the order of two discounts change the final price?
For two percentage discounts, no: 20% then 10% and 10% then 20% both leave 0.72 of the price, because multiplication is commutative. But if one is a fixed-dollar coupon, order does matter. Applying the percentage before a flat coupon gives a larger total saving, since the percentage is taken on the bigger base.
How do I find the original price before a discount?
Divide what you paid by (1 − rate). If you paid $63.75 after 15% off, the original was 63.75 / 0.85 = $75. This is useful for checking whether an advertised discount was actually applied at the register.
Which is better, a percentage discount or a fixed-dollar amount off?
It depends on the price. On a $40 item, 25% off saves $10, exactly the same as a $10 coupon; above $40 the percentage saves more, and below $40 the flat amount wins. Enter the item's price to compare the two final prices directly instead of guessing.
Does the calculator include sales tax?
No, it works only from the prices you enter. Sales tax, VAT, or GST is normally added to the discounted price afterward, so use a dedicated tax calculator alongside this one when you need the final amount including tax.