What is a Discount Calculator?
A Discount Calculator is a simple tool used to figure out the final price of an item after a "percentage off" discount is applied. It also shows you the most important number: how much money you are saving. This is the perfect tool for shoppers, helping you quickly check prices during a sale to make sure you're getting a good deal.
Whether you're looking at a 10% off coupon, a 25% off holiday sale, or a 50% off clearance event, this sale price calculator does the math for you instantly. It also works when you need to calculate sales price from a list price and percent-off label.
The Formula for Calculating a Discount
The calculation is a simple two-step process. First, you find the savings amount, and then you find the final price.
1. Amount Saved = Original Price × (Discount % / 100)
2. Final Price = Original Price - Amount Saved
Alternatively, you can find the final price in one step. If an item is 20% off, you are paying 80% (100% - 20%) of the price.
Final Price = Original Price × (1 - (Discount % / 100))
Solved Example
Let's say you want to buy a pair of shoes that are on sale:
- Original Price: $80
- Discount: 25% off
Calculation:
1. Amount Saved = $80 × (25 / 100)
2. Amount Saved = $80 × 0.25 = $20
3. Final Price = $80 - $20 = $60
The calculator would show you a Final Price of $60 and that You Saved $20.
How to Calculate a Discount With Sales Tax
In most places, sales tax is charged on the discounted price, not the original price, so you should always apply the discount first and then add tax. Here is the classic two-stage example:
A $50 backpack at 20% off, with 8% sales tax:
1. Discount: $50 × 20% = $10 off → sale price = $50 - $10 = $40
2. Add tax: $40 × 1.08 = $43.20 total bill
To add tax to any result from the calculator above, just multiply the final price by 1 + your tax rate (for example, × 1.08 for 8% or × 1.05 for 5%). Need to work out the tax portion separately? Use our VAT / GST & Sales Tax Calculator.
Reverse Discount: Find the Original Price
Sometimes you see the sale price and want to know the original price (or check that a "% off" claim is honest). To reverse a discount, divide the sale price by (1 − discount):
Original Price = Sale Price ÷ (1 - (Discount % / 100))
Example: an item costs $72 after a 20% discount. The original price was $72 ÷ 0.80 = $90. You can verify this in the calculator above by entering $90 at 20% off.
Percent-Off Quick Reference Chart
Here are the sale prices for common amounts at the most popular discount rates, so you can sanity-check a deal at a glance:
| Original |
10% off |
15% off |
20% off |
25% off |
50% off |
| $20 | $18.00 | $17.00 | $16.00 | $15.00 | $10.00 |
| $50 | $45.00 | $42.50 | $40.00 | $37.50 | $25.00 |
| $100 | $90.00 | $85.00 | $80.00 | $75.00 | $50.00 |
| $200 | $180.00 | $170.00 | $160.00 | $150.00 | $100.00 |
| $450 | $405.00 | $382.50 | $360.00 | $337.50 | $225.00 |
Practical Applications & Use Cases
This percentage off calculator is useful in many daily scenarios:
- Shopping & Sales: Quickly check the price of items during Black Friday, holiday sales, or clearance events.
- Comparing Deals: Is "30% off" at one store a better deal than "$25 off" at another? This calculator helps you compare.
- Negotiating: When buying a car or furniture, you can use this to quickly see the real price if you negotiate a "5% off" deal.
- Business Use: Business owners can use this to determine sale pricing for their own products or to calculate the cost of a discounted invoice.
Common Discount Values
While discounts can be any number, here are some common ones you'll see in stores and their quick-math equivalents:
- 10% off: The easiest one. Just move the decimal one place to the left. (10% of $80 is $8).
- 15% off: Find 10% ($8), then add half of that ($4). (15% of $80 is $12).
- 20% off: Find 10% ($8) and double it. (20% of $80 is $16).
- 25% off: Divide the price by 4. (25% of $80 is $20).
- 50% off: Divide the price by 2. (50% of $80 is $40).
Frequently Asked Questions (FAQ)
1. How do you calculate a 20% discount?
To calculate a 20% discount, convert 20% to a decimal (0.20). Multiply the original price by 0.20 to find the savings, then subtract the savings from the original price. For example, $50 at 20% off saves $10 and has a final price of $40.
2. How do you calculate percent off?
Multiply the original price by the discount percentage to find the savings, then subtract the savings from the original price. The one-step formula is final price = original price × (1 - discount percentage / 100).
3. What is 10% off of $450?
10% of $450 is $45. So a 10% discount makes the sale price $450 - $45 = $405. The same method works for any amount.
4. What is the sale price of an $880 TV after a 30% discount?
A 30% discount on $880 saves $264. Subtract $264 from $880 to get a final sale price of $616 before tax.
5. How do I calculate a discount with sales tax?
Apply the discount first, then add tax to the discounted price. Example: a $50 item at 20% off becomes $40. With 8% sales tax, multiply $40 by 1.08 to get a final bill of $43.20.
6. How do I find the original price before a discount?
Divide the sale price by (1 minus the discount as a decimal). For example, an item that costs $72 after a 20% discount originally cost $72 ÷ 0.80 = $90.
7. How do you calculate a double discount?
Apply the discounts sequentially; do not simply add them. For example, $100 with 20% off becomes $80, then an extra 10% off becomes $72. The effective discount is 28%, not 30%.
8. Does this calculator include sales tax?
Yes. Enter a sales tax percentage in the optional field to see tax and final total. If tax is left at 0%, the calculator shows the final sale price before tax.
Knowing your savings is always smart. Pair this with our VAT / GST & Sales Tax Calculator to add tax, our Markup Calculator to work pricing the other way, or, for business owners, the Profit Margin Calculator and Break-Even Point Calculator to see how discounts affect your bottom line. For a step-by-step explanation, read the discount formula and sale price guide.