Discount Calculator

Discounts multiply rather than add. Each one takes a share of whatever price is left, which is why two 25% discounts never make 50%.

• Price after first discount = original × (1 − discount ÷ 100)
• Price after second discount = that price × (1 − second discount ÷ 100)
• You save = original price − final discounted price
• Effective discount % = saved ÷ original × 100
• Sales tax = discounted price × tax rate ÷ 100, added last

The effective discount is what you actually saved as a share of the original price. Stacked discounts multiply, so two 25% cuts come to 43.75% off, not 50%.

Common mistakes and assumptions

• Adding two percentages together instead of applying them one after the other.
• Applying tax before the discount; here tax is calculated on the discounted price.
• Comparing an amount saved across different original prices instead of comparing the effective percentage.

A $240 item at 30% off with an extra 15% coupon, in a 7% sales tax state.

1. 1After 30% off: $240 × 0.70 = $168.
2. 2After the extra 15%: $168 × 0.85 = $142.80.
3. 3You save $240 − $142.80 = $97.20, an effective 40.5% discount — not 45%.
4. 4Sales tax = $142.80 × 0.07 = $10.00.
5. 5Total at the register = $152.80.

Why isn't 30% plus 15% equal to 45% off?

The second discount is taken from the reduced price, not the original. Stacking 30% and 15% gives 40.5% off; the order of the two discounts does not change the result.

Is sales tax charged before or after the discount?

After. US sales tax applies to what you actually pay, so a store coupon reduces the tax too. Manufacturer rebates are sometimes treated differently.

How do I convert "buy one get one half off"?

That is 25% off two items, since you pay 1.5 items for 2. Enter the two-item total and 25%.

Can I work backwards from a sale price?

Use the percentage calculator in "X is what percent of Y" mode with the sale price and the original price; subtract the answer from 100% to get the discount.