How we measure the tier crossing rate
The home page shows one usage figure: the share of carts that see a tier within reach and go on to cross it. Here is exactly how it is computed, so you can judge what it says and what it does not.
No figure is published yet: the measurement window is still shorter than 30 days, or fewer than 20 stores qualify. The figure appears on the home page as soon as both thresholds are met, and this page states its window and its stores.
What is counted
The bar records two anonymous signals in the storefront: a display, with the amount still missing to the next tier and the cart total at that moment, and a tier reached. A session is within reach when the bar was shown with a non-zero cart total and a tier not yet reached. A session has crossed when that same tier is reached in the same session, on the same day. Displays on an empty cart are not counted: a bar placed in a site header is shown to every visitor, and counting them would bury the rate of every store that does it.
Which stores
Every store where the bar is installed contributes, whatever its plan. A store is retained only if it totals at least 100 sessions within reach over the window, so that a handful of visits cannot swing the figure. Development, test and inactive stores (closed, frozen or paused) are excluded, based on the plan Shopify reports for them.
The window
The app folds each day into counters once the day is over. The figure uses the last 52 such days at most, and states the days it actually covers: the counters only exist since late summer of this year, and the window grows by one day every night until it is full. No day is reconstructed after the fact.
How the rate is aggregated
The published rate is the sum of crossed sessions divided by the sum of sessions within reach, across all retained stores, rounded down to the whole percent. It is the same formula a merchant reads in their own dashboard, which makes the two comparable, and it gives more weight to stores with more traffic. The median store rate is published alongside it for that reason.
What the figure does not say
It is an observation, not a cause. Carts that see a tier within reach are, by construction, carts that already contain something; some of them would have grown without any bar. The figure says what these carts do. It does not say what the bar made them do, and it does not measure an effect on average order value. That effect calls for a comparison group, which is what the holdout of the A/B testing feature provides.
Publishing rules
The figure is dated, rounded down, and computed from the counters by a script that commits its result; the site is built from that committed copy, and a test fails the build if a number is written by hand in any wording. Nothing is published under 30 measured days or 20 retained stores.