I put Trader Joe's $9 and Supergoop's $38 'invisible' sunscreen to the test, and I've already bought another bottle of the dupe

Trader Joe's website describes the $9 SPF-40 sunscreen as oil-free, translucent, and fragrance-free, which I thought was too good to be true. 

But when I squeezed some into the palm of my hand, I was impressed by the thin texture. It was different from the cream-based sunscreens I've used in the past but still felt very silky.

I was worried it wouldn't feel smooth when I rubbed it onto my face, but I was shocked by how it absorbed instantly and looked invisible.

I usually feel like there's a layer of product on my skin when I put any type of cream on it, but my skin felt bare — almost like I just had a very sheer powder on.

I went to apply my daily makeup and was nervous that my impression of the sunscreen would change. But even after I put on foundation, bronzer, and blush, my skin didn't feel weighed down with product.

The sunscreen rested well on my skin and looked more matte once I put makeup on top of it.

Though my skin felt a little more oily than usual, it was still less so than with other sunscreens or moisturizers I've tried.

I decided to do a late-afternoon, high-intensity workout class to see how the sunscreen would feel after a 45-minute sweat. 

I took off my makeup, washed my face with a cleanser, and reapplied the sunscreen before heading to class. 

Halfway through the class, I started sweating a lot more but didn't feel like the sunscreen was running down my face.

Overall, the sunscreen wasn't pilling, and it didn't make my eyes burn.

By the end of the day, I'm usually rushing to wash my face because my skin just feels so dirty and gross. But when I wore Trader Joe's sunscreen, I didn't have that same urge.

Halfway through the day, I forgot I'd even applied it.

My skin looked a little oilier than usual and my forehead had some shiny spots. But I didn't break out or feel irritated after a full day of wearing the sunscreen.

Dermatologist Noor Hanif Said from Renaissance Dermatology Specialist Clinic said one good ingredient in Trader Joe's sunscreen is octocrylene, an effective UV filter with UVB protection, the rays responsible for tanning and burning skin.

This ingredient also improves the product's water resistance, which was very useful during my workout class.

"Although it provides broad-spectrum protection, the SPF 40 rating means it blocks about 97.5% of UVB rays," Said told Insider.  

He also said that although this sunscreen is sufficient for everyday use, an SPF of 50+ might be more appropriate for extended outdoor activity.

I was excited to test out Supergoop's $38 SPF-40 sunscreen. Based on its website description, this is "100% invisible, weightless, scentless sunscreen."

When I squeezed it into my hand, it looked and felt like a liquid gel. Although it wasn't creamy, it wasn't as thin in texture as Trader Joe's sunscreen either.

The sunscreen is marketed as oil-free, but when I applied it on my face, my skin started to look oily within a few minutes.

My eyes also started to tingle a little within the first 30 minutes of application.

I applied my usual makeup on top of the sunscreen, and it glided on as if I was wearing a thin layer of moisturizer. I also felt like it gripped my makeup and made it stay on longer.

I don't usually wear moisturizer or primer, so when I wore this sunscreen all day, my skin didn't look as dry as usual, which was a nice perk. 

I took off my makeup and reapplied the sunscreen before I did a 30-minute, at-home workout. It settled onto my skin and didn't make my eyes burn this time around. 

Halfway through the workout, though, I started to sweat and it felt like the sunscreen was falling off my face. I had to take a towel to wipe it off because I was uncomfortable.

If I was doing an outdoor workout with this sunscreen, I'd especially want to reapply afterward since it seemed like most of it came off with my sweat.

Even though this formula describes itself as lightweight, I felt like I was wearing sunscreen all day. It was refreshing to take it off my skin at the end of the day. 

But I noticed that when my skin was bare, it felt healthier, which might be because the formula has a lot of antioxidant-rich ingredients.

I was expecting to break out from this sunscreen since it felt thicker than Trader Joe's formula, but I didn't. My skin felt clean and looked blackhead-free the next day.

Dermatologist Mariano Busso said that the sunscreen's key ingredients, like titanium dioxide and zinc oxide, protect against harmful UV rays. He said these provide broad-spectrum coverage, protect skin from sunburn, and lower the risk of skin cancer.

"They act as a barrier to protect the skin's surface that reflects UV rays, preventing skin penetration," Busso told Insider. "These minerals are gentle and are less likely to cause skin irritation or allergic reactions compared to certain chemical sunscreen ingredients."

Because of those benefits, I'd pick this sunscreen if I were spending the day at the beach or outside.

After trying out both sunscreens, I found myself picking up Trader Joe's bottle on a consistent basis. It didn't interfere with my makeup, workouts, or other daily activities, and it had more of a sheer, matte texture.

I was shocked that I ended up liking the less expensive sunscreen option, but it sat nicely on my skin and truly looked and felt invisible.