Thrifting is hailed as a cheap and green alternative to fast fashion. But when DW reporter Katharina Schantz set out to find the perfect pre-loved shirt, it made her question what she thought she knew about secondhand.

Secondhand is winning two-to-one on my clothing rack. It makes sense. I grew up thrifting. I'll never forget the thrill of digging up the navy-blue plush hoodie of my dreams at one of the countless flea markets I visited with my mom as a kid. But today, I'm on a smaller mission for a basic black t-shirt because I'm over the ones I have.

Since I found that hoodie, secondhand has had a serious glow up. Small, chaotic charity shops like Goodwill or Oxfam have given way to minimalistic vintage boutiques where a used shirt can cost more than a new one. And it's big business.

In 2024, the global secondhand apparel market was worth $227 billion (€194 billion) -- as much as Apple's yearly sales, according to retail analyst Neil Saunders. Younger Gen Z and millennial consumers are driving the thrifting craze -- for a few reasons.

"It's now a creative sector where people go for fun," said Saunders. "On top of that, a lot of people see it as a way of being sustainable."

And it's no wonder. Fashion is a dirty industry, responsible for up to 10% of human-made greenhouse gas emissions -- not to mention massive water use and freshwater pollution.

Then there's overproduction. The rapid turnover of cheap fashion means a truckload of clothing is sent to landfill or incinerated every second.

And some garments never even see the inside of a shop, with studies suggesting 10 to 30% of clothing is never actually sold. Most of that is treated as trash.

That's where resale -- or secondhand -- comes in. Resale promises to reduce waste and even cut fashion industry CO2. One study found that secondhand sales could slash premium apparel and outdoor brand carbon emissions 16% by 2040.

So, if resale really is part of the solution, then getting my black tee this way feels like the right thing to do.

My hunt began at Vintage Revivals, a busy store in Berlin's Prenzlauer Berg district. Clara Metzger, the store manager -- dressed in vintage from head to toe -- carefully curates her wares.

They come from Texaid, a German company for commercial clothing recycling, but Metzger said she can't resell everything. Some items go to another store that's less picky about quality.

"I weed out that kind of thing because it's pure polyester," she said, pointing to a bright turquoise headscarf. "I pick this stuff up, and feel ... yeah, it's pure trash."

Metzger has noticed a decline in the quality of secondhand clothes since fast-fashion brands like Primark and Shein started flooding the market.

But the garments she sells are a bit beyond my budget. Analyst Saunders told me the real business happens online, where 88% of US resale money was spent in 2024. So, I pick up my phone -- and discover a realm of endless choices.

Ten years ago, the online used apparel space was mainly peer-to-peer sales platforms like eBay and Poshmark, said Saunders.

"Then, a lot of retailers started taking notice. They wanted a piece of this growth," he explained. Retailers from fast fashion brands like Zara and Shein to outdoor companies like The North Face and shoe business Dr. Martens now all have online resale space.

Browsing here feels just like any other online shopping experience. The sites list items in different sizes and colors depending on availability. They give me a little boost too. I can "put things to better use" and contribute to "a better world to explore." Weirdly, it kind of makes me feel like a hero -- for shopping?

But I notice some resale platforms are closely tied to the brand's core business model of new apparel. US sportswear retailer Lululemon, for example, offers in-store credit for used items. A shirt gets you $5 and a jacket $25, but the credit can only be spent on new products.

For seasoned online shoppers, some of the sales techniques feel very familiar -- full of countdown timers and "last chance" alerts, designed to create urgency. Sellpy, a Swedish secondhand platform majority-owned by H&M, uses influencer marketing on social media.

These mechanisms often aim to increase basket size, said Martin Reimann, a marketing professor at the University of Arizona in the US.

"These same tools -- borrowed from fast fashion and e-commerce playbooks -- can reintroduce overconsumption habits into a space that was initially framed as more sustainable," he told DW. "In some cases, the line between mindful reuse and algorithmic overconsumption becomes very blurry."

In a survey of UK consumers, British NGO WRAP found that only three out of five secondhand purchases on peer-to-peer platforms like eBay or Vinted replaced new items. The other two were additional purchases that contributed to overall consumption.

To make sure resale doesn't become just another stream of revenue, experts are calling on brands to set "displacement targets." For example, a brand could pledge to replace 10% of new clothes with used apparel, which would mean a 10% cut in fresh production.

But first, companies need to be transparent about how much they're producing. Brands are often opaque around their production volume, according to The Or Foundation, a Ghanaian nonprofit seeking sustainable alternatives to the current fashion system.

So, does secondhand always deliver on its sustainability promise? Researchers from Utrecht University in the Netherlands suggested the best way to reduce emissions is to wear items longer.

The study compareddifferent types of shoppers and their emissions. They found that a fashionable secondhand consumer -- someone who buys a used shirt but only wears it 10 times before moving onto the next trend -- creates more emissions than a firsthand shopper who is really attached to their shirt and wears it 80 times.

The environmental cost of making and discarding a shirt stays with it throughout its lifecycle, no matter how many owners it has, said the researchers. For heavier items like dresses, which are typically worn less, the impact is even greater.

So, secondhand is a great way to give something a new lease of life if the item is worn a lot and consumers and retailers don't end up repeating the same patterns that have made fashion so polluting in the first place.

But in the end, my journey left me wondering whether I even needed a new shirt. The other ones in my closet might also do.

What you need to know about thrifting