To subtract a percentage from a price, multiply the price by the percentage (converted to a decimal), then subtract that amount from the original price. For example, 20% off a $80 item: $80 × 0.20 = $16 discount, so the final price is $80 − $16 = $64. There’s also a one-step shortcut that gets you there faster.
The Two-Step Method
This is the most intuitive approach. First, figure out how much money the percentage represents. Then subtract it from the original price.
- Step 1: Convert the percentage to a decimal by dividing by 100. So 25% becomes 0.25, 10% becomes 0.10, and 7.5% becomes 0.075.
- Step 2: Multiply the original price by that decimal. This gives you the dollar amount of the discount.
- Step 3: Subtract the discount from the original price.
Say you’re buying a $5,000 item at 75% off. Multiply $5,000 × 0.75 = $3,750. That’s your savings. The final price is $5,000 − $3,750 = $1,250.
The One-Step Shortcut
Instead of calculating the discount and then subtracting, you can go straight to the final price. The trick is to multiply the price by the percentage you’re keeping, not the percentage you’re removing.
If something is 20% off, you’re paying 80% of the price. So multiply the price by 0.80. A $150 jacket at 20% off: $150 × 0.80 = $120. Done in one calculation.
The formula looks like this: Final Price = Original Price × (1 − Discount Rate). The “1” represents 100% of the price, and you subtract whatever percentage is coming off. For 30% off, you multiply by 0.70. For 15% off, multiply by 0.85. For 8% off, multiply by 0.92.
Quick Mental Math Tips
You don’t always need a calculator. For 10% off, just move the decimal point one place to the left. Ten percent of $45.00 is $4.50, so the discounted price is $40.50. For 20%, find 10% and double it. For 5%, find 10% and cut it in half.
For 25% off, divide the price by 4. A $60 item at 25% off: $60 ÷ 4 = $15 discount, final price $45. For 50% off, just cut the price in half. These shortcuts work well when you’re standing in a store trying to figure out what you’ll actually pay.
Subtracting a Percentage in Excel or Google Sheets
If you’re working with a list of prices in a spreadsheet, you can apply discounts to an entire column at once. The formula Microsoft recommends is:
=B2*(1-C2)
Here, B2 holds the original price and C2 holds the discount percentage (formatted as a percentage or entered as a decimal like 0.25). The formula subtracts the discount rate from 1, giving you the “keep” percentage, then multiplies it by the price. If B2 is $200 and C2 is 15%, the result is $200 × 0.85 = $170.
If you want to apply the same discount to every row without a separate percentage column, hardcode the percentage directly: =B2*(1-0.15) gives you 15% off whatever is in B2. Copy that formula down the column, and every price gets the same discount applied.
When There Are Multiple Discounts
Things get tricky when a store offers two discounts in sequence, like “20% off plus an extra 10% off.” Your instinct might be to add them together for 30% off. That’s not how it works.
Sequential discounts compound. The second percentage applies to the already-reduced price, not the original. Take a $300 item with 10% off, then another 20% off. The first discount brings it to $270. The second discount is 20% of $270 (not $300), which is $54. Final price: $216.
If you had simply taken 30% off $300, you’d get $210, which is $6 less than the actual price. The gap grows larger with bigger numbers and bigger percentages.
There’s a formula to find the true combined discount rate without doing each step separately: Combined Discount = X + Y − (X × Y) / 100, where X and Y are the two discount percentages. For 10% and 20%: 10 + 20 − (10 × 20) / 100 = 28%. That 28% matches the real discount on the $300 item: $300 × 0.28 = $84 off, final price $216.
Adding Tax After a Discount
If you’re trying to figure out what you’ll actually pay at checkout, remember that sales tax applies to the discounted price, not the original. Take your final sale price and multiply it by (1 + tax rate). For a $120 discounted price with 8% sales tax: $120 × 1.08 = $129.60. The discount saves you money on tax too, since tax is calculated on the lower amount.