Target workers say they're walking as much as 20 miles a day. It's a sign of just how physical retail work has become.

• Retail work in the age of e-commerce and curbside pickup can be a surprisingly physical job.
• Whether picking orders or restocking shelves, their daily steps add up quickly.
• Target workers are sharing daily step counts of 20,000 or more from Apple Watches and other trackers.

Modern retail work can be a surprisingly physical job.

Walmart CFO John David Rainey pointed out in June that warehouse workers walk "up to 10 miles a day" and lift thousands of pounds — a job he said is increasingly being assisted by AI-powered robots.

Meanwhile, the industry has basically always required store workers to spend long hours on their feet, but the miles can add up quickly, especially for employees tasked with picking online orders or restocking shelves.

Plus, with the widespread use of activity trackers like Apple Watch, FitBit, and even smartphones themselves, it's getting easier for workers to see just how far they've gone during a shift at a big box store.

Over on Reddit, Target workers are posting some big numbers, often topping the 10 miles that caught the attention of Walmart's CFO.

In terms of numbers, a typical Target is roughly 125,000 square feet, which is a bit larger than two football fields. And of course, as track athletes can attest, each lap around the field is about a quarter mile.

It's not uncommon to see users sharing screenshots that show daily step counts of 20,000, with some saying the've topped 40,000 during especially busy periods like the holidays or Target Circle week.

"This week I broke my record & hit 40,000 steps in one day— gotta love Circle Week!" one user posted to the Target workers subreddit in July.

For an average-height person, 20,000 to 40,000 steps translates to 10 and 20 miles walked, or 40 to 80 laps around a typical track.

"My highest was 24,790 in a 4 hour shift. I literally don't know how I did it but fulfillment made me lose a TON of weight," another commenter said.

By comparison, a US Postal Service letter carrier in Tennessee told CNBC he typically covers 14 miles during the course of his day.

Specialty shoemaker Clove also highlighted nine other occupations that see high step-counts, with healthcare workers topping the list: some hospital staff can reach 60,000 steps, or 30 miles, during a 12-hour shift.

Of course, this doesn't all happen in one go, and the data from personal devices doesn't differentiate between steps taken on the clock or off.

A Target spokesperson told Business Insider that while the company does estimate time and distance as part of assigning work, it does not individually track employees' movements throughout the day.

In addition, like many employers, Target has mandatory break periods throughout an employee's shift when they can sit down, have a bite, and drink water.

And although the distance might sound strenuous, one worker told Business Insider that online order fulfillment is "a more active type of walking compared to stocking, and so for some people (including me) it can be more comfortable actually."

One user on Reddit asked the community for footwear recommendations since "my Converse are not comfy enough for the over 20k steps I take a shift."

Several commenters suggested Hoka and New Balance, while a few endorsed $10 running shoes from Walmart.

It's unclear which direction these numbers are trending, since fitness trackers have only become so widespread in recent years, but web and app sales figures suggest they could be going up. Target fulfills 95% of digital orders from its stores, rather than dedicated fulfillment centers, like Amazon.

After all, if more and more people are tapping an app and staying put in their cars, someone has to be running around the store on their behalf and bringing the order out to the parking lot.