How to Calculate a Discount: Formula + Simple Examples

A store advertises 25% off.

Another offers $40 off.

A website advertises 20% off plus an additional 10% discount.

Which deal is actually better?

Understanding how discounts work makes it easier to compare prices and know exactly how much you are saving.

Fortunately, calculating a discount only requires a few simple formulas.

What Is a Discount?

A discount reduces the original price of a product or service.

Discounts are commonly expressed as:

• A percentage
• A fixed dollar amount
• A promotional code
• A combination of multiple discounts

For example:

Original price: $100

Discount: 20%

Discount amount: $20

Final price: $80

How to Calculate a Percentage Discount

Use this formula:

Original Price × Discount Percentage = Discount Amount

Convert the percentage into a decimal before multiplying.

For example: 20% = 0.20

Suppose a pair of shoes costs $120 and is discounted by 25%.

Calculate: $120 × 0.25 = $30

The discount is: $30

Then subtract the discount:

$120 − $30 = $90

The sale price is: $90

Use the DailyFeedNow Discount Calculator

If you want the answer instantly, you can use our free Discount Calculator.

Enter the original price and discount percentage, and the calculator will show how much you save and your final price.

Example: 15% Off $80

Original price: $80

Discount: 15%

Convert 15% to a decimal: 0.15

Multiply: 80 × 0.15 = 12

You save: $12

Final price: 80 − 12 = $68

Example: 30% off $250

Original price: $250

Discount: 30%

Calculate: 250 × 0.30 = 75

Discount: $75

Sale price: 250 − 75 = $175

A Faster Formula for Sale Price

You can also calculate the final price directly.

If something is 25% off, you are paying 75% of the original price.

So:

Original Price × 0.75 = Sale Price

For a $120 product:

120 × 0.75 = $90

This gives you the same result without calculating the discount separately.

How to Calculate a Fixed-Dollar Discount

Some promotions use a dollar amount instead of a percentage.

For example:

Original price: $150

Discount: $25

Simply subtract: 150 − 25 = $125

Your final price is $125.

Which Is Better: $20 Off or 20% Off?

It depends on the original price.

Suppose the product costs $100.

20% of $100 = $20.

So both offers are equal.

But suppose the product costs $200.

20% of $200 = $40.

In that case:

20% off saves $40

while

$20 off saves only $20

The value of a percentage discount changes with the original price.

How to Find the Discount Percentage

Sometimes you know the original price and sale price but not the percentage discount.

Use:

Discount Amount ÷ Original Price × 100

Suppose something originally cost: $200

Sale price: $150

First calculate how much you saved: 200 − 150 = 50

Then: 50 ÷ 200 × 100 = 25%

The product was discounted by: 25%

How Do Multiple Discounts Work?

This is where shoppers often make mistakes.

Suppose a store offers:

20% off, then an additional 10% off.

That does not usually mean 30% off the original price.

Imagine the product costs $100.

First discount: 20% of $100 = $20.

New price: $80.

Now apply the additional 10%:

10% of $80 = $8.

Final price: $72.

Total savings: $28.

So the effective discount is 28%

not 30%.

The second discount applies to the already-discounted price.

Example: 30% Off Plus Another 20%

Suppose a jacket costs $200

First discount: 30%.

$200 × 0.30 = $60.

New price: $140.

Second discount:

20% of $140 = $28.

Final price:

$112.

Total savings:

$88.

$88 ÷ $200 × 100 = 44%

So 30% off followed by another 20% produces an effective discount of 44%, not 50%.

How to Calculate a Discount With Sales Tax

Depending on where you live and what you’re buying, sales tax may be added after the discounted price is calculated.

Suppose:

Original price: $100

Discount: 20%

Sale price: $80

Sales tax: 7%

Tax: $80 × 0.07 = $5.60

Final total:

$80 + $5.60 = $85.60

Tax rules vary by jurisdiction and type of product, so the exact calculation may differ.

How to Calculate Savings Between Two Prices

You may also want to compare two stores.

Store A: $150

Store B: $120

Difference: $30

To calculate how much cheaper Store B is relative to Store A:

30 ÷ 150 × 100 = 20%

Store B is 20% cheaper based on Store A’s price.

Common Discount Calculation Mistakes

One common mistake is subtracting the percentage itself from the price.

For example:

$100 − 20 does happen to equal $80.

But that only works because the price is $100.

For a $250 product, subtracting 20 would produce $230, while a genuine 20% discount gives:

250 × 0.20 = 50

250 − 50 = $200

Another common mistake is adding multiple discount percentages together.

As shown earlier, 20% off followed by 10% off is 28% off overall, not 30%.

Quick Mental Discount Tricks

You can estimate many discounts without a calculator.

10% Off

Move the decimal one place left.

10% of $80 = $8.

20% Off

Find 10% and double it.

10% of $80 = $8.

20% = $16.

5% Off

Find 10% and divide by two.

10% of $80 = $8.

5% = $4.

25% Off

Think of 25% as one quarter.

25% of $100 = $25.

25% of $80 = $20.

50% Off

Divide the price by two.

50% of $120 = $60.

Discounts and Percentage Calculations

Discount calculations are really percentage calculations.

If you’d like to understand the broader concept, read How to Calculate a Percentage: Simple Guide + Examples.

Internal link: Your percentage article.

You can also use the Percentage Calculator for other percentage problems.

Internal link: Percentage Calculator.

Does a Bigger Discount Always Mean a Better Deal?

Not necessarily.

A 40% discount sounds attractive, but the original price matters.

Product A:

Original price: $200
40% discount
Final price: $120

Product B:

Regular price: $100
No discount

Product B is still cheaper.

This is why comparing final prices is often more useful than comparing discount percentages alone.

Watch for Artificial Original Prices

A large discount can look impressive if the original reference price is unusually high.

When possible, compare:

• Final price
• Prices at other retailers
• Normal historical price
• Product quality
• Shipping fees
• Return policies

A discount is valuable only if the final purchase is actually worthwhile.

Should You Buy Something Just Because It Is Discounted?

Saving 50% on something you do not need is still spending money.

Discounts can create urgency and encourage impulse buying.

Before purchasing, consider whether you would have wanted the item without the promotion.

This simple question can prevent many unnecessary purchases.

If you’re trying to reduce unnecessary spending, read 10 Practical Ways to Save Money Every Month.

Internal link: Savings article.

Final Thoughts

Calculating a discount is straightforward once you understand the basic formula.

To find the discount amount:

Original Price × Discount Percentage

Then subtract the result from the original price.

For example:

$100 with 20% off:

$100 × 0.20 = $20 discount

$100 − $20 = $80 final price

For complicated discounts, multiple promotions, or quick calculations, use the DailyFeedNow Discount Calculator.

Knowing how discounts work can help you compare offers more accurately and make smarter purchasing decisions.