How do I calculate a discount in my head?

For 10% off, move the decimal one place left ($80 → $8 off). For 20%, double the 10% amount. For 25%, divide by 4. For 50%, just halve it. Stack these for other percentages: 30% = 10% × 3.

Is sales tax calculated before or after the discount?

Sales tax is calculated on the discounted (sale) price, not the original price. This means a bigger discount also reduces the tax you pay, giving you slightly more savings than the discount percentage alone.

Do two 25% discounts equal 50% off?

No. Stacked discounts apply sequentially. A 25% discount followed by another 25% discount gives 43.75% total savings, not 50%. The second discount applies to the already-reduced price.

How do I calculate the original price from a sale price?

Divide the sale price by (1 − discount/100). For example, if the sale price is $60 after a 25% discount: $60 ÷ 0.75 = $80 original price.

Discount Calculator

Calculate sale prices, percentage discounts, and final costs including sales tax. See exactly how much you save.

Last updated: 2026-03-07

Discount calculator

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Examples

Holiday Sale
$250 jacket at 40% off
A winter jacket marked down 40% during a seasonal sale, 8% sales tax.
Save $100 → $150 + $12 tax = $162 final
Clearance Deal
$79.99 item at 70% off
End-of-season clearance rack find, no sales tax.
Save $56 → $24 final
Electronics Promo
$1,200 laptop at 15% off
A laptop on a limited-time promotion with 6.5% state sales tax.
Save $180 → $1,020 + $66.30 tax = $1,086.30 final

How discount calculations work

A discount is a percentage reduction from the original price. The formula is simple: Sale Price = Original Price × (1 − Discount% ÷ 100).

For example, a 25% discount on a $100 item means you save $25, bringing the sale price to $75. If your local sales tax is 8%, the tax is calculated on the discounted price: $75 × 0.08 = $6.00, for a final price of $81.00.

Stacked discounts work differently than you might expect. Two 20% discounts aren't the same as one 40% discount — the second 20% applies to the already-reduced price. Two 20% discounts give you a 36% total reduction, not 40%.

Sales tax is always applied after the discount, so a bigger discount means less tax too — you save more than just the discount percentage might suggest.

Frequently asked questions

How do I calculate a discount in my head?: For 10% off, move the decimal one place left ($80 → $8 off). For 20%, double the 10% amount. For 25%, divide by 4. For 50%, just halve it. Stack these for other percentages: 30% = 10% × 3.
Is sales tax calculated before or after the discount?: Sales tax is calculated on the discounted (sale) price, not the original price. This means a bigger discount also reduces the tax you pay, giving you slightly more savings than the discount percentage alone.
Do two 25% discounts equal 50% off?: No. Stacked discounts apply sequentially. A 25% discount followed by another 25% discount gives 43.75% total savings, not 50%. The second discount applies to the already-reduced price.
How do I calculate the original price from a sale price?: Divide the sale price by (1 − discount/100). For example, if the sale price is $60 after a 25% discount: $60 ÷ 0.75 = $80 original price.

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Disclaimer

Calculations are estimates. Actual prices may vary based on additional fees, taxes by jurisdiction, or rounding at checkout. Always verify the final price at the register.

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