That is of course starting from a very low base of just 722,000 visits in January 2015, but this had risen to more than 21.4m in January 2016 according to an analysis of online behaviour by Hitwise, a division of digital advertising business Connexity.
Dollar Shave Club and Birchbox, both focused on personal care, were the top two subscription retail sites, each logging some 3.6m monthly visits, followed by Loot Crate, a curated retailer on 3.1m, Blue Apron, a fresh meal curator on 2.6m, and snack curator Graze on 1.3m.
In contrast to the astronomical growth recorded by sites such as these, visits to the top 500 non-subscription retail sites were up 168% year on year, Chain Store Age reported.
Just over half (53%) of visits to subscription retail sites came from mobile devices compared to around one third (35%) for non-subscription retailers.
And while search was the primary driver (34% vs 41% for non-subscription retailers), visitors were also significantly influenced by social media (13.5% of referred visits vs 8.4% for non-subscription retail sites).
Twitter and Pinterest are driving an enormous amount of traffic toward these shopping subscriptions, according to Hitwise.
Subscription retail also taps into the twin trends of consumers seeking out experiences and personalisation.
"What's interesting is that these players are coming up at a time when personalisation is a core value proposition," Jenny Shen, senior research analyst, beauty & CPG at benchmarking and research firm L2, told Retail Dive recently.
"Another value proposition, as with Trunk Club [where a stylist choses clothes to meet a consumer's budget and existing wardrobe], is the personalisation of the experience," she added.
The surge in sales registered by subscription sites during the holiday period also points to their role as a relatively low-cost personal gift.
Data sourced from Chain Store Age, Retail Dive; additional content by Warc staff