Discount Calculator
A discount calculator determines the final price after applying a percentage or dollar discount to an original price. Enter the original price and discount below to instantly see the sale price, amount saved, and effective discount percentage.
What Is a Discount Calculator?
A discount calculator is a tool that computes the sale price of an item after a discount is applied. It can work with percentage-based discounts (such as 20% off) or fixed dollar amount discounts (such as $15 off). The calculator also shows the total amount saved and the effective discount percentage, which is useful when comparing deals where different discount types are used.
Shoppers use discount calculators at checkout to verify sale prices, retailers use them to set promotional pricing, and businesses use them to calculate margin impact when offering discounts. This calculator also supports stacked discounts and optional sales tax so you can see the true final price. For pricing strategy tools, you can also explore the pricing calculator.
How to Calculate a Discount
Percentage Off Formula
To calculate a percentage discount, multiply the original price by the discount percentage expressed as a decimal, then subtract from the original price.
Sale Price = Original Price − Discount Amount
For example, 20% off $80: Discount = $80 × 0.20 = $16. Sale price = $80 − $16 = $64. You can also verify this using our percentage calculator for more complex percentage operations.
Dollar Amount Off
A dollar amount discount simply subtracts the fixed discount from the original price. Sale Price = Original Price − Dollar Discount. For example, $25 off $120 = $95 sale price. The effective discount percentage is calculated as: (Dollar Discount ÷ Original Price) × 100. In this example: ($25 ÷ $120) × 100 = 20.83% off.
Common Discount Calculations
10% Off
A 10% discount is the easiest to calculate mentally. Move the decimal point one place to the left. For $50, 10% off = $5 discount, sale price = $45. For $120, 10% off = $12 discount, sale price = $108.
20% Off
Calculate 10% and double it. For $50: 10% = $5, double = $10 discount, sale price = $40. For $85: 10% = $8.50, double = $17 discount, sale price = $68.
25% Off (Quarter Off)
A 25% discount equals one quarter of the price. Divide by 4 to get the discount amount. For $80: $80 ÷ 4 = $20 discount, sale price = $60. For $200: $200 ÷ 4 = $50 discount, sale price = $150.
50% Off (Half Off)
A half off calculator simply divides the price by 2. For $49.99: half off = $24.995, typically displayed as $25.00. For $130: half off = $65. The half off calculator is one of the most commonly used discount calculations during clearance sales.
75% Off
A 75% discount means you pay only 25% of the original price. Multiply the original by 0.25 to find the sale price. For $200: $200 × 0.25 = $50 sale price, saving $150. Alternatively, calculate half off and then half off again: $200 → $100 → $50.
Double Discount (Stacking Discounts)
How Stacked Discounts Work
Stacked discounts apply one discount after another. The second discount is applied to the price after the first discount has already been deducted, not to the original price. For example, 20% off followed by 10% off on a $100 item: First discount: $100 × 20% = $20 off, leaving $80. Second discount: $80 × 10% = $8 off, leaving $72. Total saved: $28.
Why 20% + 10% Is Not 30%
When discounts are stacked sequentially, they do not add together. 20% off followed by 10% off results in a 28% effective total discount, not 30%. This is because the second percentage is taken from the already-reduced price, not the original. The actual combined discount formula is: Effective Discount = 1 − (1 − D1/100) × (1 − D2/100). For 20% and 10%: 1 − (0.80 × 0.90) = 1 − 0.72 = 0.28 = 28% effective discount. Retailers sometimes advertise stacked discounts to make savings appear larger than a single equivalent discount.
Discount with Sales Tax
In most states, sales tax is calculated on the discounted price, not the original price. If an item is $100 with 20% off and 8% sales tax: Sale price after discount = $80. Sales tax = $80 × 8% = $6.40. Final price = $80 + $6.40 = $86.40. This means the tax amount is lower when you have a discount, because tax applies to the reduced sale price. Use our sales tax calculator to compute combined sales tax and discount scenarios for specific US states.
Coupons applied at point of sale reduce the taxable price in most states, further reducing the tax you pay. Rebates applied after purchase, however, do not reduce sales tax because the tax was collected at the full sale price. Always check your state's rules for coupons versus rebates.
How to Calculate the Discount Percentage
Finding What Percent Off
To find what percentage off a sale represents, subtract the sale price from the original price to get the discount amount, then divide by the original price and multiply by 100.
For example, an item originally $120 is on sale for $90. Discount amount = $120 − $90 = $30. Discount % = ($30 ÷ $120) × 100 = 25% off. This is useful for comparing deals across different stores where the same item is listed at different sale prices.
Frequently Asked Questions
How to calculate percent off?
Multiply the original price by the percentage expressed as a decimal. For 30% off $150: $150 × 0.30 = $45 discount. Sale price = $150 − $45 = $105. Alternatively, multiply by (1 − the discount rate): $150 × 0.70 = $105. This second method directly gives you the sale price without calculating the discount separately.
How much is 20% off $50?
20% off $50 = $10 discount. Sale price = $40. To calculate: $50 × 0.20 = $10 discount amount. $50 − $10 = $40 final price. You save $10, which is exactly one-fifth of the original price.
How to calculate sale price?
Sale price = Original price × (1 − discount rate). For a 25% discount on $80: $80 × (1 − 0.25) = $80 × 0.75 = $60. This formula works for any percentage discount and gives the sale price directly without computing the discount amount first.
Can you stack discounts?
Yes, but the discounts do not add together. Each additional discount is applied to the price after the previous discount. A 30% discount followed by a 20% discount gives an effective total discount of 44%, not 50%. The formula is: Effective Discount = 1 − (0.70 × 0.80) = 1 − 0.56 = 0.44 = 44%.
Is discount calculated before or after tax?
In most US states, discounts are applied before sales tax. You pay tax on the discounted sale price, not the original price. For example, 20% off $100 = $80 sale price, then 8% tax on $80 = $6.40 tax, total = $86.40. Post-purchase rebates are an exception — these do not reduce the taxable price at the time of sale.
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