After researching dozens and testing 20 pairs of socks in a locked-down London heatwave, we found the Defeet Aireator 5″ D‑Logo (Double Cuff) to be the best socks for casual use in the summer heat. We also found the Balega Hidden Comfort to be the best running socks — regardless of temperature.

The DeFeet Aireator 5″ D‑Logo (Double Cuff) were thin and airy, yet reassuringly substantial-feeling socks. Their compressive fit and light material kept our feet cool in 30°C+ (86°F+), humid weather. They strike a balance between lightness of material and cushioning, with a more dense material on the underside of the foot. The DeFeet socks were the only light feeling pair of socks that didn’t become sheer when stretched over foot. The texture on the Aireator is peculiar, varying by panel, and has a coarseness and density not seen in other socks we tested. The texture does give them a technical edge that other socks didn’t have, and that may turn off some.

DeFeet are well known in the cycling community, and with those credentials comes a couple of features. They never fall down and are designed for a compressive fit to squeeze inside road cycling shoes. They are also hard wearing. I’ve seen pairs last more than a year with no significant signs of wear and tear, although the black band on our 1 inch model did fade somewhat after a few washes and wears.

The Aireator is available in a wide range of lengths, from 1 to 6 inches, in 1 inch increments. They are available in a dizzying variety of colourways and patterns. Many of these colourways are terrible and kitschy. Highlights include sushi, doughnuts, and a unicorn on a bike in space, lowlights include ​“do epic shit”, and ​“big balls.” However we strongly advise sticking with the solid options.

It’s hard not to like DeFeet as a company. They were founded in North Carolina in 1992 by Shane Cooper, who remains CEO today. The company is still independent today too. Defeet’s socks are manufactured in their own factory in Hildebran, North Carolina in the US. Their polyester is made from recycled plastic bottles, and they have made efforts to reduce the amount of water their polyester yarn dying process consumes (more information on their manufacturing and sustainability here). Their wool is local to the USA and fully traceable. More recently Defeet published an equality statement which, to me, didn’t smack of the corporate non-speak that we’ve come to expect from brands today.

The Aireators aren’t perfect. Their thinness combined with their somewhat course texture means they don’t cope well on runs. 5 kilometre runs or shorter were passable, but longer than that resulted in some blistering — in my case on the inside of my foot. Don’t go running marathons in these.

The Balega Hidden Comfort socks are an internet darling for good reason: They stood above all others as running socks in our testing. No matter how far we ran in them, they exhibited stellar blister resistance and comfort. They were reliable, and durable. I’ve had pairs for upwards of two years — two years of multiple runs and washes per week — and they’re still holding up well, except for some light pilling. If I am getting ready for a run I instinctively reach for the Balegas.

The Balegas are on the thicker side compared to many other socks we tested. So much so that we were initially a little put off. However, anything thinner we tested ended up giving blisters in longer or hotter runs. Although they are thicker, the compromise in thickness is ultimately worth the gain in cushioning and long-term comfort. The material wicked sweat well and dried out quickly after removing your shoes post run.

Balega manufactures their socks in Cape Town, South Africa. Beyond reducing water consumption by ​“up to 50%”, Balega does not appear to have made huge efforts in improving its sustainability. It’s also disheartening to see Balega is owned by a big company that is in turn owned by a private equity firm, but it’s hard to argue with a product this good.

Material: The most important aspect and a defining factor of a sock. For socks worn in the heat, lightness and airiness are desirable. There are a large variety of materials used in socks such as cotton, wool, nylon, polyamide, and elastane among others. Cotten and linen do not perform well in hot, sweaty conditions, get wet easily and take a long time to dry. Given the more technical nature of many of these socks they tend to use synthetic fibres.

Cushioning: How much padding separates your foot from the (insole of the) shoe. The level of cushioning is inversely proportional to the thickness of the sock — the lighter the sock material, the less cushioning there is.

Blister resistance: A combination of cushioning, texture and density of weave/​material and placement of panels on the sock (if any). This mostly came into play when it came to running, particularly in distances longer than 5 kilometres.

Sweat wicking: How well the sock removed perspiration from your foot. A key point of consideration for a pair of summer socks and a couple of other use cases such as wearing boots.

Time to dry: How fast the socks will dry if they get wet — mainly with sweat but also when they get washed. Especially relevant in summer.

Compression: How compressive or tight fitting the socks are. Striking a balance is hard — too loose and the sock falls down, too tight and it becomes uncomfortable.

Seams: Where different panels of the sock attach to one another. These seams can sometimes cause irritation if they are not high quality or are in awkward places where they will be felt on your foot. Particular attention should be paid to the toe box. This wasn’t an issue in most of the socks we tested.

Origin: Where the socks are made. Many premium socks are made in developed countries. Cheaper socks tended to be made in Asia. Socks’ origins were more diverse than our other guides.

Transparency: How forthcoming the company that makes the socks is about their factory conditions. Being made in a developed country doesn’t automatically mean a factory’s conditions are good, and being made in a developing country doesn’t necessarily mean their conditions are poor. We used Good On You, a fashion brand transparency directory, to augment our research.

Company history: Has the brand been bought and sold, or is it independent? If a company has been acquired, who acquired it, and what other companies are in the acquirer’s portfolio? All things equal, preference is given to independent brands.

Cut/​length: How high the sock comes up on the leg. We looked at two main cuts: ankle and calf (or ​“crew”) cuts.

Aesthetics: Designs, graphics, logos, colours — we hate them all. Strong preference was given to socks with minimal details and available in plain colours.

Durability: Socks were worn on many walks of varying length, and on multiple 5 and 10 kilometre runs. They were washed on hot and air dried multiple times.

Price: Other than at the very cheap end, there was surprisingly little variation in pricing for mid to high-end socks. Most pairs tested fell between $12 and $20.

Purpose: Many socks are created with specific purposes in mind, such as running, cycling, hiking, and so on. We didn’t have preconceived notions about what purpose would work best for summer (casual use or sports use), so we tested a range.

Availability: We favoured socks in stock year round, that were part of a permanent collection, and available internationally. Notably a few brands were USA specific and were difficult to acquire outside the States.

A lot has been written online about socks, so we started there. 6 subreddits provided most of the recommendations: r/​malefashionadvice (post 1, 2, 3, 4, 5, 6), r/​running (post), r/​advancedrunning (post), r/​youshouldknow (post), r/​cycling (post), and r/​bicycling (post 1, post 2). We also researched what people were searching for on Google (mostly Nike). From these we compiled a short list of socks we wanted to buy and test. We bought every pair with our own money.

We weren’t sure what type of sock would work well in summer conditions, so we tried a range of different types of socks. That meant trying socks made for a range of different sports and purposes: running, cycling, hiking, etc.

We concentrated on two main cuts of sock, a mid calf (~5 inch) and an ankle cut. We tried to test at least these two from each brand, but that wasn’t always possible.

The socks we tested were worn on long and short walks in the London summer. Temperature varied wildly, but it did include a 35°C (95°F) heat wave! On these long walks, we judged how cool or hot feet felt, how comfortable feet remained over the course of the walk, and if there was any rubbing against the inside of the shoes worn. It should be noted that for the walking tests, socks were mostly worn with sneakers (specifically the Novesta Star Master — runner up in our best low-top canvas sneakers guide).

Socks were also tested for running on short to medium distances of 5 – 15 kilometres. If socks tested well at those distances, they were tested on longer runs of around 20 kilometres. For running, socks were primarily judged first for their blister resistance, secondly for their ability to keep feet feeling cool and thirdly for their ability to dry quickly after becoming wet.

Socks were washed multiple times in hot washes with detergent and fabric softener (probably against manufacturer guidelines, but who has time for that) and air dried.

All socks that were tested were rotated through over the course of two to three months, and continue to be tested today. We will update this guide if anything noteworthy comes up in the future.