As of yesterday, Jackthreads’ iPhone shopping app racked up download No. 1,000,000, the e-retailer reports. It took the members-only, flash-sale, apparel e-retailer 13 months to reach that lofty number. Further, the iPhone app currently is No. 2 on the free lifestyle app chart in Apple Inc.’s App Store and No. 27 on the free app chart for all categories, Jackthreads says.

Jackthreads was able to reach 1 million downloads because of exceptional marketing and analytics teams that analyzed Jackthreads customer data and subsequently promoted the app in the marketing channels that mattered most: Google paid search, Facebook, and sister sites including the magazine-like Thrillist, says Jason Ross, founder and CEO of Jackthreads.

“The app offers a very simple experience—we transferred some of the web experience to mobile, with a focus on shopping and driving conversion as opposed to pulling all the bells and whistles from the web and bringing them to mobile,” Ross says. Some of the bells and whistles excluded from the first version of the app were seasonal shops and content-heavy sale areas, Ross says. “Today we’re regularly seeing days where mobile commerce is driving 35-50% of revenue. We’re very much a mobile company now.”

Ross says on a typical day mobile represents 30% of traffic and 35% of revenue, and adds that his mostly male customers lean heavily toward the iPhone app. He says of the $50 million Jackthreads raked in in 2012, 20%, or $10 million, came through the e-retailer’s iPhone app, Android app, mobile commerce web site and tablets. Ross says the company has more than made back its low six-figure investment in the iPhone app.

“We’re in the process of developing an iPad app to be debuted in the second quarter,” Ross says. “We’re looking at a design refresh of the Jackthreads experience, from branding through product pages and e-mail marketing. The iPad app will start the new direction, and we will then transfer that to the web and e-mail in Q3. In the past we were thinking about how something would impact the web. Now, with every single feature we launch, we think about how it will impact the iPhone app, the Android app, the mobile web site, and soon the iPad.”

Jackthreads.com is No. 179 in the Internet Retailer Mobile 400, a compendium of the top players in mobile commerce.