Coat tag: was $199, now −40%, plus a sign "extra −20% at register." Is that 60% total or 52%? Stores stack discounts sequentially and your brain adds wrong. Knowing how to calculate discount in seconds keeps you from buying deals that are not — Black Friday included.
X% discount on price P: savings = P × (X ÷ 100); final price = P − savings. Two discounts in a row do not add: they apply one after the other on the remaining price. FORMARTIO breaks it down so you compare real offer vs noisy marketing.
Black Friday example: $199 with −40% then −20%
Original price: $199. First discount 40%: savings $79.60 → intermediate price $119.40. Second discount 20% on $119.40 —not on $199—: savings $23.88 → final price $95.52.
Real total discount: 199 − 95.52 = $103.48, equivalent to ~52% off original —not 60%. Calculate discount step by step saves you from mega-deal illusion.
Simple sale example: $35 shirt at 30% off
35 × 0.30 = $10.50 savings. You pay $24.50. If you have a $5 coupon on the already reduced price: 24.50 − 5 = $19.50 final —fixed coupon after percentage, order matters.
Sales tax and discounts
Price tagged with tax included $108.25 at 8.25% tax: base $100. 10% discount on total: you pay $97.43, do not confuse taxable base with crossed-out tag price.
Step by step to calculate discount
- Note original price or reference crossed-out price.
- List discounts in application order —store % first, then coupon.
- Open the Discount Calculator on FORMARTIO.
- Enter price and one or more percentages or fixed amounts.
- Compare final price with online marketplace before impulse buying in store.
Store tricks that confuse
"Up to 70% off" in fine print only on selected models. Inflated "reference" price before discount. BOGO is not 50% off if you did not want the second item —cheaper item free at some chains.
Calculate discount on what you would actually pay, not on manufacturer MSRP nobody charged.
For businesses: margin after markdown
Product cost $40, MSRP $80. 30% markdown: sell $56, gross margin $16 vs $40 without sale. Clear stock or destroy margin? Simulate extra units needed to compensate.
Black Friday ecommerce: WELCOME10 + SALE25 coupons. Checkout order defines final price; test both orders if the site does not document it.
Shopping sale mistakes
Adding percentages mentally. Forgetting shipping that wipes out the discount. Buying on urgency without comparing price history on Keepa or similar.
"Zero interest" financing with markup on already inflated base —fake discount.
Permanent outlet at fixed −30%: compare historical price in a tracker; calculate discount on 90-day average, not on a price never sold at that level.
10% cashback after purchase: effective discount arrives later; amount paid today is still full at register —cashback does not reduce POS total in the moment.
Buy two get one free on shoes: pay for two pairs; third free equals ~33% effective discount only if you used the third pair.
Before lining up at checkout with the red sign, run numbers on your phone. Calculate the discount on FORMARTIO, stack markdowns in the right order, and pay what it actually costs, not what the tag suggests.