20% off, then 10% off. So why isn’t it 30%?

Updated November 6, 2026

A second discount applies to the price you have left, not the price you started with. That one detail explains the whole calculation.

Follow the price, one discount at a time.

Suppose a jacket costs $100. A 20% discount saves you $20, bringing the price down to $80. Now apply an extra 10% discount. Ten percent of $80 is $8, so the new price is $72.

You saved $28 out of $100. That is a 28% effective discount. Adding 20 and 10 would suggest a $70 price and overstate the saving by $2.

A formula that works for any price.

After 20% off, you pay 80% of the price. After another 10% off, you pay 90% of that remaining amount. Multiply the amounts you keep:

Sale price = original price × 0.80 × 0.90
Sale price = original price × 0.72

For a $250 item, that becomes $250 × 0.72 = $180. You save $70, still 28% of the original price. In general, with discounts A and B expressed as percentages:

Effective discount = [1 − (1 − A / 100) × (1 − B / 100)] × 100%

Does the order change the final price?

For two percentage discounts alone, no. Multiplication gives the same result in either order. Starting with 10% off $100 gives $90; taking 20% off $90 saves $18 and again leaves $72. Intermediate savings differ, but the final amount is the same.

That does not necessarily hold when an offer includes fixed-dollar coupons, a minimum spend, shipping, or special eligibility rules. Check the offer itself. Our calculator covers one or two percentage discounts.

Where does tax fit?

If you ask the calculator to apply a 10% tax rate to the $72 discounted price, tax is $7.20 and the final amount is $79.20. The pre-tax saving remains $28. The original price and the taxed total measure different things, so compare like with like.

This is a mathematical estimate using the rate you supply. It does not decide which items are taxable, what your local rate should be, or how a retailer rounds tax across separate items.

Keep the pennies until the end.

Rounding each intermediate amount can change the final cent. Easy Calculators keeps the decimal values through the calculation and rounds the displayed monetary amounts to two decimal places using half-up rounding. A real checkout may apply item-by-item rules that differ.