Discount Calculator
Work out the sale price after a percentage discount, and how much you save.
- You save
- $20.00
This calculator provides estimates only, for general information and entertainment purposes. It isn't professional advice — confirm anything important independently before relying on it.
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How this calculator works
Enter the original price and the discount percentage to find the sale price and how much you're saving.
The amount saved is the original price × (discount% ÷ 100), and the sale price is the original price minus that amount.
Worked example: a $100 item with a 20% discount saves you $20, for a $80 sale price. Stacked discounts (e.g. "20% off, then an extra 10%") aren't simply added together — a 20% discount followed by a further 10% off the new price gives a combined 28% off the original, not 30%, since the second discount applies to the already-reduced price.
A quick reference for common discount levels on a $100 item: 10% off is $90, 25% off is $75, 33% off (a common "one third off" sale) is about $66.67, 50% off is $50, and 75% off is $25. The same percentages apply proportionally to any price — a 25% discount always leaves you paying three-quarters of the original, regardless of the starting amount.
This is useful well beyond retail sales — working out a discounted subscription price, a "member pricing" reduction, an early-bird ticket discount, or a trade-in allowance expressed as a percentage off. It's also handy in reverse during EOFY and Boxing Day sales in Australia, where retailers often advertise the percentage off rather than the dollar saving, and you want to quickly sanity-check whether the advertised sale price actually matches the claimed discount.
The most common mistake with discounts is treating percentage-off as if it were additive across multiple discounts or coupon stacking — as the worked example above shows, two 20% discounts don't combine to 40% off; they compound to 36% off (100% − 80% × 80%), because each discount is applied to an already-reduced price.
Frequently asked questions
- How do I work out two discounts stacked together?
- Apply them one after the other, not added together. For example, 20% off followed by an additional 10% off leaves you paying 80% × 90% = 72% of the original price — a combined 28% discount, not 30%.
- How do I work backwards from a sale price to find the discount percentage?
- Discount % = (original price − sale price) ÷ original price × 100. For example, if a $100 item is now $80, the discount is (100 − 80) ÷ 100 × 100 = 20%.
- Does this calculator include GST or other taxes?
- No — enter whichever price you want the discount applied to. If the original price already includes GST, the sale price shown will too; if you want the discount applied before tax, enter the pre-tax price instead.
- How much do I save with two 20% discounts compared to one 40% discount?
- Less than you'd expect. Two stacked 20% discounts leave you paying 80% × 80% = 64% of the original (a 36% total discount), while a single 40% discount leaves you paying 60% — so one 40%-off deal saves more than two 20%-off deals combined.