Last updated: October 2026
Estimate only. Tax rules vary by product, service, location and registration status. This is not professional tax or financial advice - check with a qualified adviser or the relevant tax authority.
A discount calculator works out how much you save and the price you pay: saving equals the original price multiplied by the discount percentage divided by 100, and the final price is the original minus that saving. In reverse, it finds the real percentage off from the original and sale prices.
What does the discount calculator do?
This free calculator works both ways. In saving mode, enter the original price and the discount percentage to see exactly how much you save and the final price you pay. In discount-percentage mode, enter the original and sale prices to check what percentage is really being taken off.
The formula
Saving = original price x discount % / 100, then final price = original price – saving. In reverse: discount % = (original price – sale price) / original price x 100.
Worked example
An £80 jacket at 25% off: the saving is £80 x 0.25 = £20, so you pay £60. Working backwards, a jacket reduced from £80 to £60 is (80 – 60) / 80 x 100 = a 25% discount.
What is not included
The calculator works on the sticker price. It does not add VAT, sales tax or delivery charges, and it does not stack multiple successive discounts: a further 10% off the sale price is applied to £60, not added to make 35% off.
Frequently asked questions
How do I check a shop’s claimed discount?
Use discount-percentage mode: enter the original price and the sale price. If the shop claims 40% off a £120 item but sells it for £80, the real discount is (120 – 80) / 120 x 100 = 33.3%.
Do two discounts of 20% add up to 40% off?
No. Successive discounts multiply, they do not add. 20% off then another 20% off £100 gives £64, which is a 36% total discount, not 40%.
Is VAT included in the discount?
Discounts apply to the VAT-inclusive shelf price in most shops, so the saving shown already includes the VAT portion. Business buyers should check whether quoted prices are net or gross.
How do I price a discount without losing margin?
Work backwards from the margin you need: if you need a 30% profit margin on cost and want to offer 20% off, the pre-discount price must cover both. The markup calculator can help you set it.
What is the difference between discount and markup?
A discount reduces the selling price below the marked price; markup raises the selling price above cost. They are measured against different bases, so a 25% discount and a 25% markup are not mirror images.
References
Formula background: Discount formula in maths: marked price vs selling price.
Related calculators: Profit margin calculator, Markup calculator, Business pricing calculator.
Reviewed by
Arham Arshad, founder of LancerBill, checked this tool and its calculation method in October 2026.