Guide
How to Calculate Percentage Off Any Price — Shopping Math Made Simple
Written by Calpercentage.com Team · Last updated: June 12, 2026
You're staring at a "40% off" sign, doing math in your head, and trying to decide if it's actually worth it. We've all been there.
This guide covers the three calculations you'll use over and over: finding the sale price, working out what discount you actually got, and reverse-engineering the original price. Then we'll tackle the one mistake almost everyone makes — stacked discounts.
If you just want the answer right now, use the Discount Calculator — it does all of this instantly, including stacked discounts. This article walks through the math behind it.
How to Calculate Percentage Off a Price (The Core Formula)
There are two ways to get to the same answer. Pick whichever feels more natural.
Discount = Price × (Discount % ÷ 100)
Sale Price = Price − Discount Sale Price = Price × (1 − Discount % ÷ 100) Example 1: A $120 jacket is 25% off. $120 × 0.25 = $30 off. Sale price = $120 − $30 = $90.
Example 2: A pair of shoes is £65, marked 15% off. £65 × 0.15 = £9.75 off. Sale price = £55.25.
$100 item — common discount percentages
| Discount | You Save | Sale Price |
|---|---|---|
| 10% | $10.00 | $90.00 |
| 15% | $15.00 | $85.00 |
| 20% | $20.00 | $80.00 |
| 25% | $25.00 | $75.00 |
| 30% | $30.00 | $70.00 |
| 40% | $40.00 | $60.00 |
| 50% | $50.00 | $50.00 |
| 75% | $75.00 | $25.00 |
Mental math tip: for 10% off, move the decimal point one place left. $84.00 → $8.40 off. For 20% off, just double that number.
Want to skip the arithmetic? The Discount Calculator gives you the sale price and savings instantly for any price and percentage.
How to Find the Discount Percentage Between Two Prices
Sometimes a store shows you the old price and the new price, but not the percentage off. Here's how to work it out.
Discount % = [(Original − Sale) ÷ Original] × 100 Example 1: An item drops from $80 to $60. ($80 − $60) ÷ $80 × 100 = 25% off.
Example 2: A laptop was €999, now €749. (€999 − €749) ÷ €999 × 100 = 25.03% off.
This matters most when you're comparing deals across stores and only one of them advertises a percentage. Run the numbers and you'll know which deal is actually better. This is just a percentage change calculation — our Percentage Change Calculator handles it, or use the Percentage Calculator for the raw numbers.
How to Find the Original Price Before a Discount
A friend tells you, "I got these headphones for $63 after 30% off." What was the original price? You can't just add 30% to $63 — that gives you the wrong number.
Original Price = Sale Price ÷ (1 − Discount % ÷ 100) Example 1: $63 ÷ (1 − 0.30) = $63 ÷ 0.70 = $90.
Example 2: You paid £42 after a 40% discount. £42 ÷ 0.60 = £70 original price.
This is the formula to use when you want to check if a "sale" is a real discount or if the store just marked the price up first. Reverse-engineering the original price tells you the truth.
The Stacked Discount Trap — Why 20% + 10% Off ≠ 30% Off
This is the part that trips up almost everyone. When a store offers "20% off, plus an extra 10% off," your brain wants to add those together and call it 30% off. That's not what happens.
Stacked discounts are applied sequentially — each one is calculated on the price that's already been reduced, not the original price.
Example: A $200 item with "20% off + extra 10% off."
Step 1: $200 × 0.80 = $160 (after 20%)
Step 2: $160 × 0.90 = $144 (after extra 10%)
Total discount: ($200 − $144) ÷ $200 × 100 = 28% off Not 30%. 28%. The second discount applies to a smaller number, so it's worth less in real dollars.
General formula for two stacked discounts D1 and D2 (as decimals):
Combined discount = 1 − (1 − D1) × (1 − D2) Common stacked combos — what they actually add up to
| Advertised combo | Real total discount |
|---|---|
| 10% + 10% | 19% |
| 20% + 10% | 28% |
| 30% + 10% | 37% |
| 30% + 20% | 44% |
| 50% + 20% | 60% |
| 50% + 50% | 75% |
The Discount Calculator has a dedicated stacked discount mode — add as many discounts as you like and it'll calculate the real final price and effective percentage for you.
"Buy 2 Get 1 Free" — What Percentage Off Is That Really?
These promos don't come with a percentage label, but you can translate them.
- Buy 2 Get 1 Free: you pay for 2 items, get 3. That's 1 free item out of 3, or 33.33% off the total.
- Buy 1 Get 1 50% Off: you pay 1.5x the price for 2 items, which works out to 25% off per item.
These are the conversions shoppers actually want to know but rarely see spelled out — useful for comparing a "buy more, save more" promo against a straight percentage discount.
How to Calculate Percentage Off in Excel and Google Sheets
If you're working with a list of prices, these four formulas cover everything above. Assume A1 is the original price, A2 is the sale price, and B1 is the discount percentage.
- Sale price:
=A1*(1-B1/100) - Discount amount:
=A1*B1/100 - Discount percentage:
=(A1-A2)/A1*100 - Original price:
=A2/(1-B1/100)
Format the price cells as Currency and the percentage cells as Percentage — or just enter the percentage as a plain number (like 25) and divide by 100 in the formula, as shown above.
Quick Reference — Percentage Off Cheat Sheet
Sale prices after common discounts, for a few common price points.
| Off | $50 | $100 | $200 | $500 |
|---|---|---|---|---|
| 10% | $45.00 | $90.00 | $180.00 | $450.00 |
| 15% | $42.50 | $85.00 | $170.00 | $425.00 |
| 20% | $40.00 | $80.00 | $160.00 | $400.00 |
| 25% | $37.50 | $75.00 | $150.00 | $375.00 |
| 30% | $35.00 | $70.00 | $140.00 | $350.00 |
| 40% | $30.00 | $60.00 | $120.00 | $300.00 |
| 50% | $25.00 | $50.00 | $100.00 | $250.00 |
Frequently Asked Questions
How do I calculate percentage off a price?
Multiply the original price by the discount percentage divided by 100. Subtract that from the original price to get the sale price. Example: 25% off $80 → $80 × 0.25 = $20 off → sale price is $60.
What is the formula for discount percentage?
Discount % = [(Original Price − Sale Price) ÷ Original Price] × 100. This tells you the percentage you're saving compared to the full price.
How do I find the original price before a discount?
Divide the sale price by (1 minus the discount percentage as a decimal). For example, if you paid $63 after a 30% discount: $63 ÷ 0.70 = $90 original price.
Is 20% off plus 10% off the same as 30% off?
No. Stacked discounts are applied one after the other, not added together. 20% off then 10% off a $200 item = $144, which is 28% off total — not 30%.
What percentage off is "Buy 2 Get 1 Free"?
You're paying for 2 items but receiving 3. The effective discount is 33.33% off the total, or one-third off.
How do I calculate percentage off in Excel?
Use the formula =A1*(1-B1/100) where A1 is the original price and B1 is the discount percentage. The result is the sale price after discount.
Skip the math next time.
Enter any price and discount — including stacked discounts — and get the real sale price instantly.