The honest answer is per listing
Are Black Friday deals real? Some are, substantially, and others are the price the product held in September with a percentage attached. Both are common enough that any general answer is wrong, which is why the useful version of this question is always about one listing rather than about the event.
The good news is that the check takes under a minute and does not depend on trusting anybody. Compare the offer with that product's own price history. Not with the crossed-out reference on the page, and not with what it cost last week, because last week was already inside the event's run-up. The full method sits in the pillar on whether this is a good deal.
What genuinely falls, and why
The discounts worth having share a property: a commercial reason exists for them beyond the calendar.
Stock being cleared before a replacement. This is the largest and most reliable source of a real reduction, and it is why televisions and large appliances are consistently the strongest Black Friday categories. A retailer holding floor stock of a model that a new one is about to replace is genuinely motivated, and the drop is usually larger than anything that model saw during its normal life.
Manufacturer-funded promotions. When the brand pays for the discount rather than the retailer absorbing it, the reduction can be deep and is usually available across several retailers at once. Consistency across sellers is the tell.
Categories with high seasonal inventory risk. Anything a retailer does not want to hold into January falls for real reasons: seasonal homeware, anything gift-shaped, and end-of-line clothing.
Against that, categories with steady demand and thin margins tend not to move much. Current-generation consoles, popular phones and anything supply-constrained frequently show small discounts or none, and the badges that do appear on them are the ones worth checking hardest.
The pre-sale rise
The most recognisable manufactured discount of the season works like this. A listing drifts upward through late October and early November, holds the higher price for a few weeks, then falls back to roughly where it started on the day the event begins, with a large percentage attached to the fall.
On a price history it is a hill rather than a cliff. On the listing it is invisible, because the listing shows only today and the number it chose to compare today against.
Several countries now require an advertised reference price to be one actually charged within a recent window. Where that applies, the practice does not disappear; it acquires a schedule. Hold the higher price for the required period, then discount from it lawfully. The rule improves the paperwork more than the deal, which is why the price history remains the thing to check rather than the wording on the badge.
The underlying mechanism, including the other two forms it takes, is set out in how fake discounts work.
Derivative products made for the event
A quieter practice, and one a price history cannot catch, because the product is new.
Manufacturers produce variants specifically for large sale events: a television with the same model family and a different panel, a laptop with a slower drive, a set of headphones missing a feature from the reviewed version. The model number differs by a character or two. The price is genuinely low. The product is not the one the reviews are about.
The defence is to check that the exact model number you are buying is the one the reviews and coverage discuss. If a model appears for the first time in November and vanishes in January, that is what it was for. This is not fraud and it is not hidden, but it does mean a glowing review of a nearly identical name tells you nothing about what is in the box.
The parts of the price that move without the price
A headline discount is only one of several things changing during the event, and the others are easier to miss.
Delivery terms shift. Free-delivery thresholds rise at some retailers during peak weeks, and estimated dates stretch, which matters if the purchase has a deadline attached to it.
Return windows frequently extend, and this one is in your favour. Many retailers run an extended holiday returns period covering purchases from early November into January. It is worth knowing about, because it changes what a marginal purchase costs you if it turns out wrong.
Bundles proliferate. An item that was sold alone in October appears in November with accessories attached and a combined list price, which makes a direct comparison with your own recorded figure harder and is frequently the point.
What to do before the event, not during it
The single most useful habit costs ten minutes in October.
Decide what you actually want, then record what each item costs now. That gives you a personal reference price that no badge can argue with, and it removes the event's main advantage, which is that most people do not know what anything cost a month ago.
Then during the event the question becomes simple: does this beat my October number, and by how much? A listing that does not is not a deal however large its percentage, and one that does is worth taking regardless of whether the badge looks impressive.
Two supporting habits. Check the total in the basket rather than the headline, because delivery terms and coupon conditions change more during promotional periods than at any other time of year. And treat countdowns as what they are: a reduction in your checking time rather than information about the price.
The categories worth ignoring entirely
Some things reliably do not fall, and knowing which saves the most time of anything on this page.
Current-generation consoles at launch demand. Popular phones in their first year. Anything supply-constrained, where the retailer has no reason to discount stock that sells at full price. Staples with thin margins and steady demand, where there is no room to move.
On those, a November badge is almost always measuring against a reference rather than a history, and the genuine price movement will come later, from a product cycle rather than a promotional calendar.
Cyber Monday, and whether waiting helps
Cyber Monday skews toward smaller electronics, online-only stock and categories where the retailer has inventory left after the weekend. Sometimes prices fall further; sometimes the best items are gone.
Waiting for it is a reasonable bet on a specific category and a poor general strategy. If the thing you want is already below your October number and in stock, the marginal gain from waiting three days is usually smaller than the risk of it selling out. If it has barely moved, waiting costs nothing and the extra days give the pre-sale rises time to be visible.
The broader question of when prices genuinely fall, and which categories move on predictable cycles rather than promotional calendars, is covered in when prices actually drop.
The one-minute version
Ignore the percentage. Find the product's own price range over the last year and the level it usually sits at. Put today's price against that level. If today is clearly below it, the discount is real whatever the badge says. If today is inside the usual band, the badge is measuring against a reference rather than a history, and the event has not changed anything about this product except its marketing.
To run that comparison on a specific listing during the event rather than in the abstract, use the Amazon deal checker.
