Percentage discount or fixed coupon: which deal is cheaper after shipping?
Compare offers by the final amount paid, including coupon rules, delivery charges and the tax treatment of discounts.
How to calculate it
For a percent discount, sale price = original price × (1 − rate). For a fixed coupon, subtract its face value only if the basket meets any minimum and the relevant items are eligible. Add shipping and tax in the order required by the store and local rules. Some coupons do not apply to delivery or taxes; some percentage offers exclude sale goods or have a maximum cap. Write each offer as a separate calculation.
Worked example
Suppose an item costs 80. Offer A is 20% off plus 8 shipping, giving 64 + 8 = 72 before tax. Offer B is a 15 fixed coupon plus free shipping, giving 65 before tax. B is cheaper by 7, even though 20% of 80 is 16 and appears larger than 15. If offer B requires a minimum basket of 100, it does not apply to the single item; do not invent an eligible discount.
What can change the result
At a different price the winner changes: a 20% discount on 150 saves 30, which beats a fixed 15 before shipping. Returns, restocking fees, subscription commitments and delivery times can also matter. Tax rules vary: do not assume tax is always computed on the discounted subtotal. Compare the actual checkout totals when available.
Use the calculators and keep reading
Run each offer through the discount calculator, add the shipping charge, and use sales tax only under the rule at checkout. Compare unit price if quantities differ. The related stacked-discount guide explains why two successive percentages do not simply add.
Try the discount, sales tax, unit price calculator and read this related article for the context and assumptions.