Savings Tool
Discount
Calculator
Final Price
£0.00
You Save
£0.00
Work out exactly how much you save on any purchase. Enter the original price, choose a discount percentage or pick a preset, and see the final sale price instantly. Need to stack two discounts together? Enable the second discount to see how sequential markdowns affect the total. You can also enter a quantity to find the price per unit after discount.
Price & Discount
Final Price
£0.00
You Save
£0.00
Discount Amount
£0.00
Effective Discount
0%
Price Per Unit
£0.00
Breakdown
Original Price
£0.00
After 1st Discount
£0.00
After 2nd Discount
£0.00
Total (x Qty)
£0.00
How the discount calculator works
Enter the original price of the item and the discount percentage you want to apply. The calculator multiplies the price by the discount rate to find the savings amount, then subtracts it from the original price to give you the final sale price.
If you have a stacked discount — for example, a store-wide 20% sale plus an extra 10% voucher — enter the second percentage in the "Extra Discount" field. The calculator applies the first discount to the original price, then applies the second discount to the already-reduced price, just like a retailer would.
You can also enter a quantity if you are buying multiple items at the same discounted price. The calculator shows the total cost and the price per unit, making it easy to compare deals across different shops or pack sizes.
What you need to know about discounts
A single discount is straightforward: multiply the original price by (1 minus the discount rate). A £100 item at 25% off costs £100 × 0.75 = £75. The savings are £25.
Stacked discounts are applied sequentially, not added together. A 20% discount followed by an extra 10% off does not equal 30% off. The first discount reduces £100 to £80. The second 10% applies to the £80, saving £8, for a final price of £72. A straight 30% off would give £70 instead. The effective combined rate of stacked discounts is always slightly less than the sum of the individual rates.
The mathematical formula for stacked discounts is: Final Price = Original × (1 − d1) × (1 − d2), where d1 and d2 are the decimal discount rates. The effective single-discount equivalent is: 1 − (1 − d1) × (1 − d2).
When comparing deals, always look at the final price rather than the headline discount percentage. A "50% off" sale on an inflated list price may cost more than a "20% off" deal on a fairly priced item. Use this calculator to compare the actual amounts you would pay.
Frequently asked questions
How do I calculate a discount on a price?
Enter the original price and the discount percentage into the calculator. It multiplies the price by the discount rate and subtracts that amount to give you the final sale price. For example, 20% off £100 means you save £20 and pay £80.
How do stacked discounts work?
Stacked discounts apply sequentially, not combined. A 20% discount followed by an extra 10% off does not equal 30% off. The first discount reduces the price, then the second discount applies to the already-reduced amount. 20% + 10% off £100 gives £72, not £70.
What is the formula for calculating a discount?
The discount formula is: Final Price = Original Price × (1 − Discount Rate). For a £50 item at 25% off: £50 × (1 − 0.25) = £50 × 0.75 = £37.50. The savings amount is £50 − £37.50 = £12.50.
How do I calculate the price per unit after a discount?
Divide the final discounted price by the number of items. If you buy 3 shirts originally priced at £40 each with a 25% discount, the total is £90. The price per unit is £90 ÷ 3 = £30 per shirt.
Is 20% off plus 10% off the same as 30% off?
No. Stacked discounts are applied one after the other, not added together. 20% off £100 gives £80, then 10% off £80 gives £72. A straight 30% off £100 would give £70. Stacked discounts always save you slightly less than the combined percentage.
How do I work out how much I save with a discount?
Subtract the final price from the original price. If an item costs £80 and is 15% off, the sale price is £68. Your savings are £80 − £68 = £12. The discount calculator shows both the savings amount and final price automatically.