How Often Should You Wash Jeans? What the Evidence Says

How often should you wash jeans? Levi's own current care advice says about every 10 wears, inside out, in cold water on a gentle cycle, then air dry in the shade. Wash sooner if they're dirty, sweaty or smelly (that last bit is our common-sense addition, not a source). Spot-clean small stains first. The much-repeated “never wash your jeans” idea turns out to be a lot more nuanced than the headlines, and the freezer trick doesn't work.

What the Levi's CEO actually said

In May 2014, Levi's CEO Chip Bergh spoke at the Fortune Brainstorm Green conference in Laguna Niguel, California. Levi's own post (May 20, 2014) quotes him calling jeans “the ultimate in slow fashion” and joking that they outlast waistlines. The “stop washing your jeans” line is the post's paraphrase, not a direct quote. We could not verify the often-repeated “I've never washed these jeans” line in that post, so we won't repeat it. The post also says roughly half of a pair's water use comes from production and half from home laundering.

The numbers behind the advice

Levi's published a life cycle assessment of its 501 jeans in 2015. Its March 26, 2015 post reports:

• Washing every third wear instead of every second can cut climate and water impacts by up to 20 percent.
• A cold-water wash cuts non-renewable energy use by 21 percent and climate impact by 24 percent (US figures).
• Line-drying instead of machine-drying cuts non-renewable energy by 64 percent and climate impact by 67 percent.
• Consumer use and cotton growing use the most water, and Americans have the highest water and energy use of the countries studied.

A Fortune article from March 2015 reports bigger figures: nearly 3,800 liters of water and 33 kilograms of carbon per pair, and an 80 percent cut from washing every 10 wears instead of every 2. Those aren't on Levi's March 26 page, and a January 2015 Levi's post gives 919 gallons per pair instead, so the numbers vary by study version. We stick with the Levi's page figures. Using cold water matters because heating water is the biggest energy cost of washing (see which wash temperature for which clothes).

What happens if you don't wash for 15 months?

A University of Alberta student, Josh Le, wore a pair of raw denim jeans for 15 months and one week before the first wash, airing them three times a week. Swabs (2011 university report) found per square centimeter about 8,000 to 10,000 bacteria in the crotch, 1,500 to 2,500 on the back and 1,000 to 2,000 on the front. No E. coli or other lower-intestinal bacteria turned up, only common skin bacteria. Growth was “virtually the same” after 15 months unwashed as two weeks after washing. But it was one person and one pair, and textile scientist Professor Rachel McQueen said bacteria come mostly from the wearer and she does not recommend waiting a year or more.

The freezer trick does not work

The idea is to put jeans in the freezer to kill bacteria. In a 2014 NBC Bay Area demo, Stanford microbiology doctoral student Adam Perez swabbed jeans before and after an overnight freeze and concluded freezing did not reduce bacteria, saying bacteria are “designed to be able to freeze.” He noted that a lab freezer is colder than a home one. A Levi's spokesperson said the company changed its position “following further studies” and that Bergh never endorsed freezing. It was a TV-station demo, not a peer-reviewed study, but the result is consistent.

The history: rivets, riveted pockets and the word “jeans”

The Smithsonian's National Museum of American History says Jacob Davis, a Latvian-born tailor in Reno, reinforced pockets with copper rivets after a customer kept tearing his. He asked Levi Strauss to co-patent the idea, and Patent 139,121 was granted on May 20, 1873. The patent expired in 1890, and early rivets are stamped “L. S. & CO. S. F. PAT. MAY 1873.” The first “waist overalls” were made of duck, a heavy canvas, before denim. Levi's history page says they were called waist overalls until 1960, when baby boomers adopted the word “jeans.”

An older story: a Smithsonian Magazine piece describes the unidentified 17th-century “Master of the Blue Jeans,” whose ten paintings show denim-like clothing. A gallery owner, Maurizio Canesso, says jeans come from Genoa and denim from Nîmes. He has a commercial interest in those paintings, and the article itself gives two different dates for early blue dye, so file that as interesting but weakly sourced. Sanforizing, the process that pre-shrinks denim, was developed by Sanford Lockwood Cluett in the late 1920s with patents around 1930, per a denim enthusiast site (Heddels). It says sanforized fabric shrinks no more than about 5 percent, versus up to about 10 percent unsanforized. We could not verify when Levi's adopted it.

Raw denim culture

Enthusiast site Denimhunters says frequent washing removes indigo evenly for a vintage fade, while infrequent washing gives sharper contrast but more “blowouts.” That's opinion, not testing. For other denim posts, see faux denim vs real denim and what vintage wash means.

Jeans washing myths, graded

Sources & further reading

• Levi Strauss & Co. (2014), Chip Bergh at Fortune Brainstorm Green
• Levi Strauss & Co. (2015), 3 surprising insights about those 501 jeans
• Fortune (2015), wash your jeans once every 10 wears
• Levi's care guide
• University of Alberta (2011), Jeans remain surprisingly clean after a year of wear
• NBC Bay Area (2014), Cleaning your jeans by freezing them
• Smithsonian, Levi's rivet patent and Levi's history of denim
• Smithsonian Magazine, When were blue jeans invented
• Heddels, What is sanforization and Denimhunters, raw denim washing guide (enthusiast sites)