In 1926, Joseph and Clara Pilates opened the world’s first-ever Pilates studio at 939 Eighth Ave. One hundred years and 40 blocks later, Manhattan will soon become home to the world’s largest.

“I had no idea going into it that we were opening the biggest studio,” Reforming Pilates owner Genevieve Ross, 34, told The Post. “But my husband called and said, ‘This is the most incredible space I’ve ever seen in my life. There is nothing like it.’ He signed [the lease] on the spot. I didn’t even see the space because I had just given birth.”

Reforming Pilates Townhouse is scheduled to open on June 1 in a three-story, nearly 7,000-square-foot space at 109 W. 17th St. in Flatiron. The lease is for 10 years, but other terms of the deal were not disclosed.

The former carriage house, with its red-brick facade, is 25 feet wide and was built in 1920, according to records. It will be the company’s second New York location; there is already a two-story studio on the Upper East Side.

“The townhouse has great bones, beautiful lighting and old fireplaces,” Ross said.

Despite likely being the largest studio in the world — there are several boutique studios around 6,000 square feet: a Lagree studio in Toronto, New York Pilates’ Flatiron location, and a yoga and Pilates studio in Austin, Texas) — the new Reforming Pilates Townhouse won’t be overrun with reformers. The space has two separate equipment rooms, capped at 10 reformers each, plus an infrared-heated mat Pilates room and a place for private classes.

Keeping each space small was important for quality control, “so the instructors can do hands-on modifications and can see everyone,” Ross said.

Reforming Pilates opened its first location in Miami in 2021. It has since expanded to nine studios in Florida and New York, not including this townhouse, with at least three more in the works. Two are in Florida and one will be in Manhattan’s Murray Hill. The growth has been all word-of-mouth, Ross said.

“We have spent, to this day, $0 on ad spend,” Ross said. “We don’t do Google ads, we don’t do anything like that. It’s all been just opening where our clients wanted us to go.”

Pilates has exploded in popularity since the early days of the pandemic for many reasons: an increase in overall health trends; the practice can be adapted for all levels; there are several ways to participate — a mat, a reformer, a tower, a chair; and based on the millions of photos on Instagram and TikTok touting a #PilatesBody, it works. It also looks cool on social media. Unless specifically banned, you’ll be hard-pressed to find a class today without someone’s phone stuck to the wall filming themselves for content, for better or worse.

Aesthetically, the new Reforming Pilates Townhouse also looks good on camera, with muted hues, neon signs, curved furniture and herringbone floors. The townhouse was designed by the same team that fashioned the also-born-in-Miami Pura Vida restaurant chain, Ross added.

However, the practice is also quite pricey — while the cost varies, on average, reformer classes around the country tend to hover around $35 for a single class, while monthly unlimited packages can reach $300 to $600. (Classes at Reforming Pilates’ Upper East Side location are $50 for a single class, a 10-pack for $330, and $599 for an unlimited, one a day, monthly pass.) Still, there are plenty of free Pilates mat classes online. Pilates By Izzy, for example, has amassed almost 2 million subscribers on YouTube with her mat routines and challenges.

Meanwhile, based on current trends, no one seems to mind the cost. A new report from Allied Market Research projected that the Pilates and yoga market will grow 14.3% globally, jumping from $120 billion in 2025 to around $521 billion by 2035.

In the US, about half the total retail square footage in 2025 was leased by service-related businesses, including spas, salons, sauna and plunge studios, and yoga and Pilates gyms, according to CoStar data. In New York City, fitness- and wellness-related leases have surged around 40% year-over-year, according to research from Newmark, a commercial real estate advisory firm.

Jeff Roseman, vice chairman at Newmark, told The Post: “Fitness and wellness have made a huge impact in the retail landscape over the past few years.”

And people will travel for what they want. Deb Huberman, a 40-something producer working in fashion, has been taking classes at Reforming Pilates’ Upper East Side location near her home but says she plans to head downtown when the new Reforming Pilates Townhouse opens in the coming weeks

“I’m 100% going to the new location,” Huberman told The Post. “Especially because they are also going to have hot Pilates, which I really like.”

Looking ahead, Ross has more plans for expansion in Manhattan, the Tri-State area, Florida and California.

“What keeps people coming back is how they feel, and they know how important they are in our community,” Ross says.