How to Prevent Swim Goggles from Fogging Up: Proven Tips for Clear Vision

To take the straightest possible line through the course and achieve your best time, you need to be able to see the course-marking buoys or pool floor. However, as all swimmers have experienced, whether in the pool or open water, goggles fog up from time to time. That can cause you to take a longer line and increase the total distance of your race.

Thankfully, foggy goggles can be avoided with the right preparation. In this article, we’ll explain why swimming goggles fog up, how to stop it, and how to prolong the lifespan of your goggles.

Why Do Swim Goggles Fog Up?

In short, swimming goggles fog up due to the temperature difference between your body and the water you’re swimming in.

Whenever you don your goggles, you’re essentially creating a sealed chamber where moisture is trapped and continues to gather as you swim. The air inside this chamber contains moisture, and your skin and eyes shed more moisture.

Additionally, while you swim and your body produces heat, it continues to warm the air in the chamber, increasing the difference in temperature between inside and outside.

When you start swimming, your goggles meet the water, which cools the lenses, because the water is usually colder than the inside of the goggles. When the warm, moist air inside the goggles touches the cold lens, the air immediately next to the lens cools down. Cold air cannot hold as much moisture as warm air, so the excess water vapour is forced to convert back into water. The temperature at which this conversion happens is called the dew point.

When water gathers in this way, the individual molecules attract one another through a force called surface tension, forming tiny droplets with curved surfaces. In swimming goggles, these curved droplets cause the light to scatter in a way that makes the lens look opaque or foggy to your eyes.

This is where anti-fogging agents (surfactants) come into play. Surfactants disrupt the surface tension of water by binding to and repelling the individual molecules, causing them to spread out evenly on the surface that allows light to pass through. In the case of swimming goggles, this helps maintain a visually clear lens despite the buildup of condensation in the lenses.

Another everyday example of this is on a summer’s day, you’ll notice that liquid condenses from moisture in the warm air and builds up on the outside of any glass containing a cold drink.

Common Causes of Fogging

The best swimming goggles are treated with an anti-fogging agent that, for a period of time, prevents fogging. However, over time, this effect fades as the anti-fogging layer breaks down. This happens through touching or rubbing the lenses, their exposure to chlorine or saltwater, and the accumulation of dirt and oils from your skin and hair.

How to Stop Swimming Goggles From Fogging Up — Household Products, Dedicated Products, and Last-Resort Methods to Prevent Fogging

If the treatment on your goggles is working well, let it do its job. However, if it never had any anti-fog or it’s losing its effectiveness, follow these steps to prevent your swimming goggles from fogging before training or racing.

• Wash your goggles after every swim. If they don’t have anti-fog treatment, you can use hand soap to effectively remove any dirt and oil before applying your own anti-fog treatment. If they do have anti-fog, wash them with cold tap water and air-dry, as outlined below.

• Once clean, there are a couple of everyday household products that swimmers recommend as anti-fog surfactants. You can try ‘no tears’ baby shampoo or toothpaste.

• Before application, wash your hands to remove oils. Then, take a small drop of the product on your fingertip and rub it over the inside of the lenses to create a thin film. Allow the product to dry for about one minute, then lightly rinse the goggles to remove any excess. Don’t wash the product off completely, as this will negate the anti-fog effect.

• Anti-fog spray or anti-fog wipes are dedicated products that, in theory, should last longer and perform better than the abovementioned household products. Follow the manufacturer’s guidelines when using these products.

• If you’re stuck without any of the above options, saliva can act as a temporary surfactant, as many swimmers attest to. Spit on the inside of the lenses and lightly spread the saliva around. Before putting them on, give them a quick rinse under a tap or dunk them in the pool or sea.

• If you splash your face with cold water before starting your swimming session or between laps, you can delay the onset of fogging. This is because cooling your face reduces the temperature difference between the inside and outside of the goggles.

Swim Goggles Maintenance Tips and Common Mistakes to Avoid

Here are some tips to prolong the life of the anti-fog treatment that your goggles come with and avoid damaging it:

1. Wash your goggles with cold tap water after every swim. This rinses them of any saltwater, chlorine, or other chemicals.
2. Don’t touch or rub the lenses to clean or dry them. This friction breaks down the anti-fog. Residual salt from sea swimming is highly abrasive, so rubbing a lens with salt on it greatly increases the rate of wear.
3. After rinsing, let your goggles air-dry (don’t put them straight into the protective case).
4. Don’t leave them to dry in the sun. The heat may degrade the anti-fog treatment.
5. Once dry, return your goggles to their case to avoid scratching the anti-fog layer. A hard case is more protective than a soft case.
6. Don’t place the goggles on your head between sets; this allows heat from the top of your head to build up and oils from your hair to contaminate the lenses. Instead, keep them in your hand or at the side of the pool.

When to Replace Your Swimming Goggles

It’s not possible to provide an exact timeframe for replacing your swimming goggles. Some anti-fog treatments are better than others, but the most important factor determining how long they last is how well you maintain them (following the dos and don'ts above).

However, all goggles reach a point when they begin fogging shortly after entering the water. In this situation, you can try treating them with household products or anti-fog sprays or wipes to temporarily restore their anti-fog properties. However, their days are numbered at this point.

Other issues that indicate it’s time to buy a new set include:

• Leaking: If the lens seal gets damaged, water will enter and negatively impact vision, even if the anti-fog is working.

• Scratched Lenses: Scratches obscure vision independent of fog, and they damage the anti-fog treatment.

• Strap damage: If the straps lose their elasticity or get damaged, the goggles will allow water to enter and not remain securely in place.