Discount Calculator

Quick reference for the sale price at common discount percentages. Format: final price you pay / amount you save.

Stacked discounts don't add: 20% then 10% off is 28% total, not 30%. Use the stacking feature above to model 'extra X% at checkout' deals correctly.

The discount calculator finds the sale price and how much you save from any percentage off. It handles stacked discounts (the 'extra 10% at checkout' kind), shows the effective total percentage, and can add sales tax to give you the real out-the-door cost.

Single discount

sale price = original × (1 − discount). For 25% off $80: 80 × 0.75 = $60. You save 80 × 0.25 = $20.

Finding the original price

If you know the sale price and the discount: original = sale price / (1 − discount). A $60 item at 25% off was originally 60 / 0.75 = $80. Useful for checking whether a 'was $X' claim is honest.

When you stack discounts, they multiply - they don't add. This is the single most common shopping math error.

20% off then an extra 10% off a $100 item:

• Step 1: 20% off $100 = $80
• Step 2: 10% off $80 = $72
• Total off: $28, or 28% - NOT 30%

The order doesn't matter (10% then 20% gives the same $72), but the result is always less than the sum of the percentages. The formula for two stacked discounts: effective = 1 − (1 − d1) × (1 − d2). For 20% and 10%: 1 − 0.8 × 0.9 = 0.28 = 28%.

A fast percentage off calculator table for common sale prices and discounts. Each cell is the final price you pay after the discount.

To read the amount saved instead, subtract the cell from the original price. For example, 40% off $200 leaves $120, so you save $80.

Every percentage discount calculator uses the same one-line formula: multiply the price by 1 minus the discount written as a decimal. To get the discount percentage calculator result in your head, convert the percent to a decimal and multiply.

How do I calculate 20 percent off?

Twenty percent off means you pay 80 percent. 20 percent off 45 = 45 × 0.80 = 36. The amount you save is 45 × 0.20 = 9. That is the quick answer for any "how do I calculate 20 percent off" question.

The 10 percent then double trick

For a fast mental estimate, find 10 percent by moving the decimal one place to the left, then double it for 20 percent. For $45, 10 percent is $4.50, double it to $9 saved, so you pay $36. Halve the 10 percent figure for 5 percent, or add it on for 15 percent.

What is 40 percent off?

Forty percent off means you pay 60 percent of the price. 40 percent off 200 = 200 × 0.60 = 120, so you save $80. That is the core of any 40 percent discount calculator: the decimal multiplier is 1 - 0.40 = 0.60.

A double discount, or two stacked discounts, does not add up the way it looks. Percentages multiply. If a $100 item is 30 percent off and then an extra 20 percent off at checkout, you pay 0.70 × 0.80 = 0.56 of the price.

• Step 1: 30% off $100 = $70
• Step 2: 20% off $70 = $56
• Total off: 44%, not 50%

So the combined double discount is 44 percent, not the 50 percent you would get by adding 30 and 20. The general rule for stacked discounts is effective = 1 - (1 - d1) × (1 - d2), which always lands below the simple sum.

To work out the original price before a discount, divide the sale price by 1 minus the discount: original = sale price / (1 - discount). This reverses the discount so you can check a "was $X" claim.

Example: an item rings up at $36 after 20 percent off. The original price before the discount was 36 / 0.80 = 45. For a $90 item that was 25 percent off, the starting price was 90 / 0.75 = 120.

When you need a discount calculator with tax, apply the discount first, then add sales tax to the reduced price. Tax is charged on what you actually pay, never on the original price.

• Start: $100 item, 25% off, 8% sales tax
• Discount: 100 × 0.75 = $75
• Tax: 75 × 1.08 = $81 out the door

As one line: final = original × (1 - discount) × (1 + tax). Applying the discount first is how a receipt reads and keeps the percent saved figure honest.

How do I calculate 25% off?

Multiply the price by 0.75 (which is 1 − 0.25). $80 × 0.75 = $60. Or find the savings first: $80 × 0.25 = $20 off, leaving $60.

What's 30% off $50?

$50 × 0.30 = $15 off, so the sale price is $35. Quick mental math: 10% of $50 is $5, so 30% is $15.

How do I add tax after a discount?

Apply the discount first, then add sales tax to the discounted price - tax is charged on what you actually pay. Our optional tax field handles the order automatically.

Is a bigger percentage always a better deal?

Not necessarily. 50% off an overpriced item can still cost more than 20% off a fairly priced one. Always compare the final price against what the item actually sells for elsewhere, not just the discount size.

How do I reverse-engineer the original price?

Divide the sale price by (1 − discount as decimal). $45 after a 25% discount: 45 / 0.75 = $60 original. Handy for verifying 'reduced from' claims.

How do stacked or double discounts work?

Two discounts multiply rather than add. A 30 percent then 20 percent double discount is 0.70 × 0.80 = 0.56, so you pay 56 percent and save 44 percent, not 50. Stacked discounts always save less than the two percentages added together.

How do I find the original price before a discount?

Divide the sale price by 1 minus the discount as a decimal. A $36 price after 20 percent off means the original price before the discount was 36 / 0.80 = 45.

Can I use this as a percent off calculator for sale prices?

Yes. It works as a percent off calculator, a discount sale calculator, and a percentage off calculator for sale prices: enter the price and the percent off to see the final price and the amount saved instantly.