Discount Calculator
Calculate the sale price after a percentage discount. See how much you save on any purchase.
What Is a Discount Calculator?
Sale season in the UK means a lot of percentages, some of which are more meaningful than others. A 40% off sign is straightforward. A 'Was £89.99, Now £59.99' label requires mental arithmetic most people don't bother with in the moment — which is precisely why retailers use that format. This calculator does it instantly.
The UK Consumer Rights Act requires that sale prices shown as reductions must reflect the genuine previous selling price. In practice, this is often stretched — '50% off' against a reference price that was only on sale for a day or two is a common retail tactic. Knowing the actual discount percentage helps you judge whether a deal is real.
Enter the original price and either the discount percentage or the sale price. You'll see the saving in pounds, the discount percentage, and the final price you'd pay.
How Do You Use This Discount Calculator?
Enter the original price and the discount percentage. Click Calculate to see the discount amount and the final sale price.
- Enter the original price in pounds.
- Type the discount percentage (e.g., 20 for 20% off).
- Press Calculate to see the discount amount and final price.
- Review the savings summary showing pounds saved.
- Adjust the percentage to compare different discount levels.
- Use the result to compare against competing offers.
How Does the Discount Calculator Formula Work?
The formula used: Discount Amount = Original Price × (Discount % / 100). Sale Price = Original Price - Discount Amount
The discount amount equals the original price multiplied by the percentage as a decimal: Discount = Price × (Percentage / 100). A 25% discount on £200 is 200 × 0.25 = £50.
The sale price is Sale Price = Original Price - Discount Amount, so £200 - £50 = £150.
For stacked discounts, apply each one sequentially: Price after first = Price × (1 - D1/100), then Price after second = Price after first × (1 - D2/100). Stacked discounts always yield a smaller total reduction than adding the percentages together.
What Are Some Example Calculations?
Original price £120 with 25% off: Discount = £30. Sale price = £90. You save £30.
Winter sale: £250 jacket at 40% off
£250 × 0.40 = £100 discount. £250 - £100 = £150.
Sale price: £150. You save £100.
Stacked promotion: £80 shoes at 20% off + extra 10% off
£80 × 0.80 = £64 after first discount. £64 × 0.90 = £57.60 after second.
Final price: £57.60. Total saving: £22.40 (28% effective discount).
Grocery deal: £3.50 item at 15% off
£3.50 × 0.15 = £0.53 discount. £3.50 - £0.53 = £2.97.
Sale price: £2.97. You save £0.53.
When Should You Use a Discount Calculator?
Before buying anything with a percentage-off label. Enter the original price and discount to confirm the sale price before you get to the checkout. Useful for online shopping where the displayed saving can sometimes be based on a recommended retail price rather than what the item actually sold for.
When comparing sale items across retailers. If one retailer has 30% off and another has 25% off but started with a lower base price, converting both to their final prices makes the comparison objective. The calculator with the higher percentage isn't always the better deal.
What Do These Terms Mean?
How Do the Options Compare?
| Original Price | First Discount | Price After First | Second Discount | Final Price | Effective % |
|---|---|---|---|---|---|
| £100 | 20% | £80 | 10% | £72 | 28% |
| £100 | 30% | £70 | 10% | £63 | 37% |
| £100 | 25% | £75 | 25% | £56.25 | 43.75% |
| £100 | 50% | £50 | 20% | £40 | 60% |
| £100 | 10% | £90 | 5% | £85.50 | 14.5% |
What Are the Best Tips to Know?
- Compare the discounted price against other retailers rather than focusing on the percentage alone.
- Calculate stacked discounts separately. A 20% + 10% discount is 28% off, not 30%.
- Check whether the discount applies to the original RRP or an already-reduced price.
- Factor in delivery charges after calculating the discount to see the true total cost.
- Use the calculator to verify store-displayed sale prices are correct.
What Mistakes Should You Avoid?
- Adding stacked percentages together (20% + 10% = 30%) instead of applying them sequentially (actual: 28%).
- Forgetting to include VAT when comparing pre-tax trade prices against retail sale prices.
- Assuming a higher percentage discount always saves more money. 50% off a £20 item saves less than 20% off a £200 item.
- Ignoring delivery fees that can wipe out the saving from a small discount.
Frequently Asked Questions
How do I calculate 20% off a price?
Multiply the price by 0.20 to find the discount, then subtract from the original price. For £50: discount = £10, sale price = £40. Or multiply by 0.80 directly.
How do stacked discounts work?
Stacked discounts are applied one after another, not added. A 20% discount followed by a 10% discount on £100: first £100 × 0.80 = £80, then £80 × 0.90 = £72. This is less than a single 30% discount.
What is the difference between a percentage discount and a fixed discount?
A percentage discount reduces the price by a proportion (e.g., 20% off). A fixed discount reduces by a set amount (e.g., £10 off). Percentage discounts save more on expensive items.
Does the order of stacked discounts matter?
No. Applying 20% then 10% gives the same result as 10% then 20%. Multiplication is commutative so the final price is identical regardless of order.
How do I reverse-calculate the original price from a sale price?
Divide the sale price by (1 - discount/100). For a £60 sale price after 25% off: £60 / 0.75 = £80 original price.
Is a £10-off coupon better than 10% off?
It depends on the price. On a £50 item, 10% off saves £5 while £10 off saves £10. On a £200 item, 10% off saves £20 while £10 off still saves only £10.
How do I calculate the savings on a buy-one-get-one-half-price deal?
Add the full price and half price together. For two £40 items: £40 + £20 = £60 total. The saving is £20, which equals a 25% effective discount across both items.
Can I use this for VAT-inclusive prices?
Yes. Enter the VAT-inclusive price as the original price. The discount applies to whatever figure you enter. Use the VAT calculator separately if you need to isolate the tax component.
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