Most people picture a sale as a switch. One day the signs go up, some weeks later they come down, and in between it's "the sale" — one thing, the same on every day of it.
After a year of tracking real, verified sale activity across UK shopping centres, I can tell you that's not what a sale looks like at all. A sale is a curve. It rises, it spends time at the top, and — this is the part almost nobody knows — while it's up there, the discounts get deeper. Then it recedes. Every centre-wide sale season we've recorded has this same shape, and once you see it, you can't unsee it on a rack of red signs again.
The rise: shops join one by one
A centre-wide sale doesn't start everywhere at once. A handful of keen brands flip first — often mid-season stock they want gone early. Days later, more follow. Then the big anchors move, and suddenly what was three shops with a rail at the back is half the centre with windows full of red.
On a Tide card this is the score climbing: 8% of tracked shops on sale, then 15, then 30. The first day the calendar calls it "the summer sales", the curve has barely left the floor. That's why the opening weekend so often disappoints — you're visiting a sale that exists mostly in the future.
The top: where a sale spends its time — and quietly cuts deeper
Here's the counterintuitive bit. The top of the curve isn't a single day. A centre that peaks doesn't spike and collapse; it holds — often for a week or more, with most of the shops that are going to join already in.
And while the number of shops on sale stops climbing, the sale itself isn't standing still. It's doing something quieter: deepening. A shop that opened its sale at "up to 50% off" marks the same rail down to 60%, then 70%, as the weeks pass and stock needs to move. We see this constantly in the verified data — a sale that's been running for two or three weeks suddenly cuts deeper, mid-cycle, with no new signage drama at all.
So a sale really has two phases stacked on top of each other:
- Breadth — how many shops are on sale. This is what the headline Tide Score measures, and it peaks first.
- Depth — how hard those shops are discounting. This keeps building after breadth has flattened, which is why the amber average discount figure on a centre's page can still be climbing while the score holds level, and why individual shops light up as "just got deeper" during the plateau.
The plateau is where those two lines cross: nearly everything that's going to be on sale is on sale, and the cuts are at or near their deepest — while the good stock, crucially, hasn't all gone yet.
The fall: it recedes
Then it ends — but not with the synchronised sign-ripping-down you might imagine. Shops drop out the way they came in: one by one. Sold-through brands quietly go back to full price, the rails shrink to a single picked-over corner, and the score eases down the far side of the curve. What's left late in a cycle is real — often the deepest percentages of the whole sale — but it's the leftovers: broken size runs, the colours nobody wanted.
The curve on the centre's history chart tells you which side of the hill you're on. The same 35% score means completely different things on the way up (building, fresh stock) and on the way down (receding, remnants).
Why the shape matters more than the dates
Every sale guide tells you when sales happen — Boxing Day, late June, Black Friday. Almost none tell you that within each of those windows there's a rise, a plateau and a fall, and that the plateau is where breadth and depth meet.
That's the entire reason Tide exists: the calendar can tell you the season, but only live tracking can tell you where on the curve your centre is today — how many shops are genuinely on, whether the discounts are still deepening, and which way the tide is moving. As I write this, in late July, most of the centres we track are past the breadth peak of the summer season and well into the deepening phase — scores holding or easing while average discounts keep creeping up.
Pick your centre, look at the curve, and read the tide for yourself.