How to Calculate Discounts: Percent vs Dollar, Stacking, and Final Totals

Understand the math behind promotions so you can compare real totals across stores.

Fast path: run scenarios in /finance/discount-calculator.

Percent vs Dollar Discounts

• Percent: new price = price × (1 − percent). Example: 20% off $80 → $64.
• Dollar: new price = price − amount. Example: $15 off $60 → $45.

Which is better depends on the price. For small carts, dollar‑off can win; for larger carts, percent‑off often wins.

Stacking and Order of Operations

Two 20% discounts are not 40%. They apply sequentially to the reduced price.

Example: $100 → 20% off = $80 → another 10% = $72 (not $70).

General sequence:

1. Apply percent/dollar discounts in the terms’ order
2. Add tax/fees to the discounted price
3. Add shipping

Worked Comparisons

• Cart A: $150 with 25% off → $112.50; $10 ship; 7% tax → ~$130.38
• Cart B: $150 with $30 off → $120; free ship; 7% tax → ~$128.40 → Cart B wins despite smaller headline discount.

Common Traps

• “Up to” language—your item may not qualify for the max percent.
• Hidden shipping or platform fees that erase savings.
• Minimum spend thresholds that change the order total when items go in/out of cart.

FAQs

Why aren’t two 20% discounts equal to 40% off? Because the second 20% applies to a smaller base.

Is a dollar or percent discount better? It depends on the pre‑discount price and fees. Do the math—or plug it into the calculator.