Shopping CalculatorsDiscount, sales tax, unit price & deal math in seconds
Shopping calculators are free tools that show the real price you pay before you reach the checkout. Use them to work out a percent-off sale price, stack two discounts, add or remove sales tax, compare price per ounce, judge a BOGO or Black Friday deal, and see what Buy Now, Pay Later or tariffs actually cost you.
- 14 free calculators
- Formulas shown openly
- No sign-up, runs in your browser
- Reviewed Oct 2026
By Manzoor Ahmad · 13+ years of web development & SEO · Updated October 25, 2026
What will I actually pay?
Enter the tag price and any discounts. Extra % off is applied to the already-reduced price, the way stores stack offers.
Need more detail? Use the Discount and Tax Calculator.
Discount & Sale Price Calculators
Every “% off” question, from a single markdown to stacked coupons and the original price behind a sale tag.
Discount Calculator
Start here. Enter a price and a percentage or dollar discount to get the sale price, the amount saved and the effective discount rate.
“How much is 30% off $65?”
Open Discount Calculator Discount CalculatorPercent Off Calculator
Built for the sale rack: type the tag price and the “% off” sign and see what you pay, with a quick table for common markdowns.
“What is 40 percent off $120?”
Open Percent Off Calculator Percent Off CalculatorDouble Discount Calculator
Shows why “20% off plus an extra 10%” is a 28% discount, not 30%, and works out the final price for two or three stacked offers.
“25% off, then take another 15% off?”
Open Double Discount Calculator Double Discount CalculatorOriginal Price Calculator
Works backwards from a sale price and the discount to find the list price, so you can check whether the “was” price is believable.
“It’s $48 after 20% off — what was it?”
Open Original Price Calculator Original Price CalculatorBOGO Calculator
Converts “buy one get one free”, “BOGO 50% off” and “buy 2 get 1” into a real per-item price and percentage discount.
“Is BOGO 50% off really half price?”
Open BOGO Calculator BOGO CalculatorBlack Friday Calculator
Total a whole holiday cart with different discounts per item, sales tax and a spending cap, then compare it with your gift budget.
“How much will my Black Friday cart really cost?”
Open Black Friday Calculator Black Friday CalculatorPrice After Tax Calculators
The sticker price is rarely the register price. These tools put sales tax in the right place.
Discount and Tax Calculator
Applies the discount first, then sales tax, and returns the out-of-pocket total. It also flags manufacturer coupons, which many states tax on the pre-coupon price.
“30% off $79.99 plus 7% tax?”
Open Discount and Tax Calculator Discount and Tax CalculatorReverse Sales Tax Calculator
Pulls the tax back out of a receipt total to reveal the pre-tax price, useful for expense reports, returns and price matching.
“My total was $108.25 at 8.25% — what was the price?”
Open Reverse Sales Tax Calculator Reverse Sales Tax CalculatorOut the Door Price Calculator
Adds sales tax, title, registration and dealer fees to a car’s negotiated price, minus rebates and trade-in, so you negotiate the real number.
“What’s the out-the-door price on a $32,000 car?”
Open Out the Door Price Calculator Out the Door Price CalculatorCompare Value Calculators
Bigger pack or smaller pack? Cheap item or durable one? Compare what each unit, ounce or use really costs.
Unit Price Calculator
Compares two to four products by price per item, per pound, per kg or per liter and tells you which one is the better buy and by how much.
“Is the 12-pack or the 30-pack cheaper per can?”
Open Unit Price Calculator Unit Price CalculatorPrice Per Ounce Calculator
Handles mixed units — ounces, fluid ounces, pounds and grams — so you can compare cereal, coffee, detergent or baby formula fairly.
“24 oz for $4.29 or 40 oz for $6.49?”
Open Price Per Ounce Calculator Price Per Ounce CalculatorCost Per Wear Calculator
Divides the price of clothing, shoes or gear by how often you will use it, so a quality coat and a fast-fashion one can be compared honestly.
“$180 boots worn 150 times vs $60 worn 20?”
Open Cost Per Wear Calculator Cost Per Wear CalculatorPayments & True Cost Calculators
How you pay and where a product comes from both change the final cost. These tools make that visible.
Buy Now Pay Later Calculator
Splits a purchase into pay-in-4 or monthly installments, shows each due date, and adds the cost of late fees or interest on longer plans.
“What are the payments on $400 in 4 installments?”
Open BNPL Calculator Buy Now Pay Later CalculatorTariff Price Impact Calculator
Estimates how much a tariff could add to the shelf price of an imported product — including the extra sales tax charged on that higher price.
“How much more will a $999 laptop cost with a 10% tariff?”
Open Tariff Calculator Tariff Price Impact CalculatorBudgeting & Daily Finance
Once you know a purchase’s true cost, see how it fits your month with the 50/30/20 Budget Calculator or your savings with the Emergency Fund Calculator.
“Can I afford this purchase this month?”
Visit Finance CalculatorsWhich Shopping Calculator Do I Need?
Match the question in your head to the right tool. Each one answers a single shopping decision well, rather than one tool doing everything badly.
| Your question | Use this calculator | What you get |
|---|---|---|
| How much is X% off this price? | Percent Off Calculator | Sale price and dollars saved |
| The store added an extra % off at checkout | Double Discount Calculator | Final price and true combined discount |
| What was the price before the sale? | Original Price Calculator | List price from sale price and % |
| What will I pay at the register? | Discount and Tax Calculator | Total after discount and sales tax |
| How much tax is inside my receipt? | Reverse Sales Tax Calculator | Pre-tax price and tax amount |
| Which pack size is cheaper? | Unit Price Calculator | Price per unit and the better buy |
| Is BOGO worth it? | BOGO Calculator | Real price per item and % saved |
| Should I split this into payments? | BNPL Calculator | Installment schedule and fee risk |
Shopping Math Formulas Every Calculator Uses
We publish the formulas so you can check any result by hand. Percentages are written as decimals (20% = 0.20).
Sale price after a discount
Sale price = Price × (1 − d)$80 at 25% off → 80 × 0.75 = $60.00
Two stacked discounts
Final = Price × (1 − d1) × (1 − d2)$80, 25% then 10% → 80 × 0.75 × 0.90 = $54.00 (32.5% total)
Original price before a sale
Original = Sale price ÷ (1 − d)$48 after 20% off → 48 ÷ 0.80 = $60.00
Price after sales tax
Total = Price × (1 + t)$54 at 8.25% tax → 54 × 1.0825 = $58.46
Remove tax from a total
Pre-tax = Total ÷ (1 + t)$108.25 at 8.25% → 108.25 ÷ 1.0825 = $100.00
Unit price
Unit price = Price ÷ Quantity$4.29 ÷ 24 oz = $0.179/oz vs $6.49 ÷ 40 oz = $0.162/oz
BOGO effective discount
Discount = Free value ÷ Full value of all itemsBOGO 50% on two $40 items → $20 ÷ $80 = 25% off, not 50%
Cost per wear
Cost per wear = Price ÷ Times used$180 ÷ 150 wears = $1.20 vs $60 ÷ 20 wears = $3.00
Percent Off Chart: What You Pay on $100, $50 and $25
Shortcut: multiply the price by the percentage you still pay. 30% off means you pay 70%, so $50 × 0.70 = $35.
| Discount | $100 item | $50 item | $25 item |
|---|---|---|---|
| 10% off | $90.00 | $45.00 | $22.50 |
| 15% off | $85.00 | $42.50 | $21.25 |
| 20% off | $80.00 | $40.00 | $20.00 |
| 25% off | $75.00 | $37.50 | $18.75 |
| 30% off | $70.00 | $35.00 | $17.50 |
| 40% off | $60.00 | $30.00 | $15.00 |
| 50% off | $50.00 | $25.00 | $12.50 |
| 70% off | $30.00 | $15.00 | $7.50 |
How to Calculate the Real Price of a Sale Item
A $80 jacket is marked 25% off, you have a 10%-off coupon, and local sales tax is 8.25%. Here is the order stores actually use:
- Apply the advertised discount. $80 × (1 − 0.25) = $60.00.
- Apply the coupon to the reduced price. $60 × (1 − 0.10) = $54.00. The coupon never applies to the original $80.
- Add sales tax to the discounted price. $54 × 0.0825 = $4.46, so the total is $58.46.
- Check the true saving. $80 − $54 = $26 saved, which is 32.5% — not the 35% the two signs suggest.
5 Shopping Math Mistakes That Cost You Money
Adding stacked discounts together
20% off plus 20% off is 36% off, not 40%. The second discount only applies to what is left.
Subtracting tax as a percentage of the total
Taking 8% off a $108 receipt gives $99.36, not $100. Divide by 1.08 instead.
Trusting the “compare at” price
The FTC’s pricing guides warn against inflated former prices. Check the original price, not just the percentage.
Comparing package prices, not unit prices
Bigger packs are usually cheaper per ounce — but not always. Check the unit price label or calculate it.
Treating BNPL as free money
Pay-in-4 plans are often interest-free when paid on time, but late fees and overlapping plans add up quickly.
Shopping Calculator Questions, Answered
A shopping calculator is a tool that works out the real cost of a purchase — the sale price after a discount, the total after sales tax, the price per unit, or the cost of paying in installments — so you can compare deals before you buy.
Multiply the original price by the discount as a decimal to get the savings, then subtract it. For 25% off $80: 80 × 0.25 = $20 saved, so the sale price is $60. A faster method is to multiply by what you still pay: 80 × 0.75 = $60.
No. Stacked discounts multiply rather than add. 20% off and then 10% off leaves you paying 0.80 × 0.90 = 72% of the price, which is a 28% total discount. Use the Double Discount Calculator to check any combination.
For store discounts and store coupons, sales tax is normally charged on the reduced price. Manufacturer coupons are different: many US states tax the price before the coupon because the retailer is reimbursed for it. Rules vary by state, so check your state revenue department if the amount matters.
Divide the sale price by the percentage you paid. If an item is $48 after 20% off, you paid 80% of the price, so the original price is 48 ÷ 0.80 = $60.
Divide the total by one plus the tax rate. A $108.25 total at 8.25% tax was $108.25 ÷ 1.0825 = $100.00 before tax, so the tax was $8.25.
Unit price is the cost per ounce, pound, liter or item. It lets you compare products sold in different sizes. Many grocery shelf labels show it, but the unit used can differ between labels, so a calculator keeps the comparison fair.
Only if you wanted both items and they cost the same. BOGO free on two $40 items is $40 for $80 of goods, a 50% discount. BOGO 50% off is $60 for $80 of goods, a 25% discount. If you only needed one, you saved nothing.
Short pay-in-4 plans are usually interest-free if every payment is made on time, but late fees can apply. Longer monthly BNPL plans may charge interest like a loan. The Consumer Financial Protection Bureau has studied BNPL use and noted the risk of stacking several plans at once.
A tariff is a tax paid by the importer. Part or all of it is often passed on to shoppers as a higher shelf price, and sales tax is then charged on that higher price. How much reaches you depends on the product, the country of origin and how much the seller absorbs.
Yes. Every calculator on dexocalc.com is free, needs no account, and runs in your browser, so the prices you enter are not sent to us.
Manzoor Ahmad
Founder of DexoCalc · 13+ years of web development & SEO experience
Manzoor builds and maintains every calculator on DexoCalc. Each shopping tool is tested against hand-worked examples, its formulas are published on the page, and results are checked against official guidance such as the FTC’s pricing guides and state sales tax rules.
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Last reviewed and updated: October 25, 2026
Sources & References
- Federal Trade Commission — Guides Against Deceptive Pricing (16 CFR Part 233)
- National Institute of Standards and Technology — NIST Handbook 130: Uniform Unit Pricing Regulation
- Consumer Financial Protection Bureau — Buy Now, Pay Later: Market Trends and Consumer Impacts
- Tax Foundation — State and Local Sales Tax Rates
- Yale Budget Lab — State of U.S. Tariffs (April 2026)
Disclaimer: DexoCalc shopping calculators provide estimates for planning and comparison. Store policies, coupon rules, local sales tax rates and tariff pass-through vary, so your receipt may differ. These tools are not financial, legal or tax advice.