Discount Calculator | Percent Off, Sale Price & Savings
Calculate the final price after any discount, find the original price from a sale price, apply two stacked discounts sequentially, and add sales tax. Covers percentage off, fixed amount off, reverse calculation, and double discounts.
Applied after discount
Discount Formulas All Four Scenarios
Every discount calculation falls into one of four scenarios. Here are the exact formulas with worked examples for each:
1. Find the final price after a % discount
Final = Original × (1 − Discount% ÷ 100)$120 item, 30% off → $120 × 0.70 = $84
You save: $36
2. Find the original price (reverse calculation)
Original = Sale Price ÷ (1 − Discount% ÷ 100)Item costs $84 after 30% off → $84 ÷ 0.70 = $120
Original was: $120
3. Find the discount percentage
Discount% = ((Original − Sale) ÷ Original) × 100$120 original, $84 sale → ((120−84) ÷ 120) × 100 = 30%
Discount: 30%
4. Find the amount saved
Amount Saved = Original Price × Discount% ÷ 100$120 item, 30% off → $120 × 0.30 = $36 saved
Saved: $36
How Stacked Discounts Work and Why You Can't Add Percentages
When a store offers 20% off and you also have a 10% coupon, most people assume the total discount is 30%. It is not. Stacked discounts apply sequentially the second discount applies to the price after the first discount, not the original price.
Example: $100 item 20% store sale + 10% coupon
Step 1: $100 × (1 − 0.20) = $80 after first discount
Step 2: $80 × (1 − 0.10) = $72 after second discount
Total saved: $100 − $72 = $28 (28% effective discount — not 30%)
The combined formula for any two stacked discounts is: Final = Original × (1−D₁) × (1−D₂). For three stacked discounts, extend the same pattern. The effective combined percentage is always less than the sum of individual discounts.
Percentage Off vs. Fixed Amount Off Which Saves More?
The better deal depends entirely on the original price. At a certain price point, both discounts save the same amount. Above that point, the percentage discount wins. Below it, the fixed discount wins.
| Original Price | 20% Off (saves) | $30 Off (saves) | Better Deal |
|---|---|---|---|
| $50 | $10.00 | $30.00 | $30 fixed wins |
| $100 | $20.00 | $30.00 | $30 fixed wins |
| $150 | $30.00 | $30.00 | Tie at exactly $150 |
| $200 | $40.00 | $30.00 | 20% wins by $10 |
| $500 | $100.00 | $30.00 | 20% wins by $70 |
The crossover point for 20% off vs $30 off is $150 at that exact price both discounts save the same. Formula: Crossover Price = Fixed Amount ÷ (Discount% ÷ 100).
The Psychology Behind Discounts How Retailers Use Pricing to Influence Buying
Understanding how retailers design discount offers helps you evaluate deals more objectively before spending.
The Anchoring Effect
Retailers display the original price prominently so it serves as an anchor. A price of $72 feels cheap when shown next to a crossed-out $120. Without that anchor, $72 is just $72. Research in behavioral economics (Kahneman, Thaler) consistently shows that people judge value relative to an initial reference point, not in absolute terms. Always ask: was this item ever actually sold at the 'original' price?
Artificial Urgency
"Only 3 left!" and "Sale ends midnight" create time pressure that overrides rational comparison. A 2020 study by the Journal of Consumer Research found that scarcity cues increase purchase intent by up to 50%, even when the scarcity is artificially created. If a retailer runs the same "48-hour flash sale" every week, the urgency is not genuine.
Charm Pricing ($9.99 vs $10)
Prices ending in .99 or .95 are perceived as significantly lower than the next round number. MIT and University of Chicago research found that demand for items priced at $39 was higher than for the same items at $34 — simply because $39 is a "just-under" price while $34 reads as a less-discounted round number. This effect is called the "left-digit effect."
The BOGO Trap
Buy-one-get-one-free offers are 50% off per unit but only if you would have bought two items anyway. If you buy a second item only because it is "free," you are actually spending 100% more than you intended. Retailers know that BOGO promotions increase average basket size significantly. Ask yourself: would you buy this item at full price without the deal?
When Prices Are Lowest Seasonal Discount Calendar
Retailers follow predictable discount cycles tied to inventory clearance and major retail events. Knowing these cycles lets you time purchases to maximize savings without relying on luck.
January
Winter clothing, holiday decor, furniture, gym equipment
Post-holiday inventory clearance + New Year fitness gear returns
July
Summer clothing, swimwear, outdoor furniture, Amazon Prime Day deals
Mid-year clearance + Amazon Prime Day (electronics, tech)
August
Laptops, backpacks, school supplies, clothing
Back-to-school season electronics especially
October
Halloween items, some appliances (pre-Black Friday test sales)
Pre-holiday promotional period begins
Black Friday (Nov)
TVs, appliances, gaming, clothing, toys
Largest US retail event Adobe Analytics: $9.8B spent in 2023
Cyber Monday (Nov)
Software, online subscriptions, tech, clothing
Online-only extension of Black Friday
December 26+
Holiday decor, gifts, winter clothing, toys
Post-Christmas inventory liquidation deepest discounts of the year
5 Rules for Evaluating Any Discount Offer
Verify the original price has actually been charged.
In the US, the FTC requires that advertised 'original' prices must have been offered in good faith for a meaningful period. Many retailers inflate the original price before a sale. Use CamelCamelCamel for Amazon products or Google Shopping history to verify the item's actual price history.
Calculate the final price, not the percentage saved.
"50% off" on a $200 item and "10% off" on a $90 item both save $10. The percentage off is meaningless without knowing the original price. Always calculate how many dollars you actually save, then decide if the final price is worth what you are paying.
Use the stacked discount calculator before accepting multiple offers.
A store discount plus a coupon plus a loyalty card discount applied sequentially is always less than the sum of those percentages. A 20% + 15% + 10% stack gives a 38.8% combined discount, not 45%.
For fixed vs. percentage off, calculate the crossover point.
Use the formula: Crossover = Fixed Amount ÷ (Discount% ÷ 100). If a $25-off coupon competes with a 15%-off sale, the crossover is $25 ÷ 0.15 = $167. Items priced above $167 favor the 15% discount; below $167, take the $25 off.
Never buy something you did not plan to buy just because it is discounted.
A 50% discount on something you did not need still costs 50% of its full price. The best discount is the one on something already on your shopping list. Make your list before browsing sale pages, not after.
Frequently Asked Questions
Common % Discounts
Common Fixed Discounts
Final Price
Original × (1 − D%)
Amount Saved
Original × D%
Original Price
Sale ÷ (1 − D%)
Discount %
((Orig − Sale) ÷ Orig) × 100
Stacked (D1+D2)
Orig × (1−D1) × (1−D2)
With Tax
Final × (1 + Tax%)
Check price history before Black Friday many items are inflated then discounted back to normal.
Fixed discounts beat percentage discounts on cheaper items. 20% off $50 = $10 saved; $15 off = $15 saved.
Stacked discounts always give less than the sum of both percentages. Use the Stacked tab to get the real number.
Post-Christmas (Dec 26–31) has the deepest discounts of the year up to 80% on holiday inventory.
The price at which both discounts save the same amount. Above this price, % off wins. Below it, fixed wins.