How to use the discount calculator
- Enter the original price.
- Enter the discount percentage.
- Optionally enter a second discount applied after the first, such as a coupon on a sale price.
- Optionally enter a sales tax rate to add at the end.
- Read the final price, the amount saved and the total discount.
Formulas
- After discounts = price × (1 − d1) × (1 − d2).
- Saved = price − after discounts.
- Total discount = 1 − (1 − d1) × (1 − d2).
- Final price = after discounts × (1 + tax).
Worked examples
- Single discount: $120 with 25% off = $90; you save $30.
- Stacked discounts: $120 with 25% off, then 10% off = $81; you save $39, a total discount of 32.5%.
- With sales tax: $81 plus 8% sales tax = $87.48.
Stacked discounts explained
When a shop advertises “an extra 10% off sale prices”, the extra discount is taken from the already reduced price. That is why two discounts are always worth less than their sum. Two 50% discounts give 75% off, not 100%. The calculator shows the true combined discount so you can compare offers.
Tips for shoppers
- Compare final prices, not discount percentages.
- Check the original price; inflated “was” prices make discounts look bigger.
- Factor in shipping and return costs.
- Watch for minimum spend conditions on coupons.
- Stick to your budget; a discount on something you don’t need isn’t a saving.
Tips for sellers
Discounts reduce your margin more than you might expect. On an item with a 40% margin, a 25% discount cuts the profit per sale by more than half. Use the margin and markup calculator to check the margin left after a discount, and the break-even calculator to see how many extra sales you would need.
Percentage off versus amount off
Some offers are a fixed amount, such as $20 off. To compare with a percentage offer, divide the amount by the price: $20 off $120 is about 16.7%. For cheaper items a fixed amount is worth relatively more; for expensive items a percentage usually wins.
Working backwards
Sometimes you know the sale price and want to check the advertised discount. Divide the sale price by the original price and subtract the result from 1: $81 ÷ $120 = 0.675, so the real discount is 32.5%. If a shop claims a bigger discount than this calculation shows, the advertised “was” price or the discount terms deserve a closer look.
Limitations
The calculator handles up to two percentage discounts and one tax rate. Fixed-amount coupons, bundles and tiered discounts must be converted to percentages first.