Discount Calculator

Common Discounts

10% off$100 = $90
20% off$100 = $80
25% off$100 = $75
30% off$100 = $70
50% off$100 = $50

How to Calculate Discounts

Basic Discount Formula

Calculating discounts is a fundamental math skill useful for shopping, budgeting, and business. The basic formula to find the sale price after a percentage discount is:

Sale Price = Original Price x (1 - Discount Rate)
Or equivalently: Sale Price = Original Price - (Original Price x Discount Rate)

Example Calculations

Example 1: 25% Off $80

Discount = $80 x 0.25 = $20
Sale Price = $80 - $20 = $60
You save $20!

Example 2: Find Original from $60 at 25% off

Original = $60 / (1 - 0.25)
Original = $60 / 0.75 = $80
Original price was $80

Understanding Stacked Discounts

When multiple discounts are applied sequentially (not added together), the calculation changes. For example, a 20% off coupon on an item already 30% off:

Stacked Discount Example

Original: $100, First discount: 30% off, Second discount: 20% off

After 30% off: $100 x 0.70 = $70
After 20% off: $70 x 0.80 = $56
Total savings: $44 (44% off, not 50%!)

Quick Mental Math Tips

10%
Move the decimal one place left. 10% of $45 = $4.50
20%
Find 10% and double it. 20% of $45 = $4.50 x 2 = $9.00
25%
Divide by 4. 25% of $80 = $80 / 4 = $20
50%
Divide by 2. 50% of $65 = $32.50

Sales Tax Considerations

In most places, sales tax is calculated on the discounted price, not the original price. This means your tax bill is also reduced when you get a discount.

ScenarioBefore Tax8% TaxTotal
Original $100$100.00$8.00$108.00
With 25% off$75.00$6.00$81.00

Smart Shopping Tip

Before making a purchase, calculate the actual discount to ensure you're getting a good deal. Sometimes "50% off the second item" or "buy 2 get 1 free" offers aren't as good as they sound compared to a straight percentage discount.

Frequently Asked Questions

How do I calculate a discount percentage?

To find the discount percentage: Discount % = ((Original Price - Sale Price) / Original Price) x 100. For example, if an item was $80 and is now $60: (($80 - $60) / $80) x 100 = 25% off. This helps you compare deals across different items or stores.

How do I calculate the sale price after a percentage discount?

Multiply the original price by (1 - discount rate). For 30% off a $50 item: $50 x (1 - 0.30) = $50 x 0.70 = $35. Alternatively, calculate the discount amount ($50 x 0.30 = $15) and subtract it from the original price ($50 - $15 = $35).

How do stacked discounts work?

When discounts are stacked (applied sequentially), they multiply rather than add. For 30% off plus an additional 20% off: First discount gives you 70% of original, then the second discount gives you 80% of that result. So 0.70 x 0.80 = 0.56, meaning you pay 56% of original (44% total discount, not 50%).

Is 'buy one get one 50% off' the same as 25% off each?

Yes, mathematically they're equivalent for two items. If each item is $40: BOGO 50% = $40 + $20 = $60 for two. 25% off each = $30 + $30 = $60 for two. However, 'buy one get one free' (BOGO free) equals 50% off total, which is a better deal than 25% off each item.