How Much SPF Should I Use? And More Sunscreen Questions

Sunscreen is a hot topic in the skincare world that sparks a lot of questions. Let’s say, you’ve heard that SPF is important in sunscreen. What does that really mean? Is SPF 30, 45, or 50 better? Well, we’ve got the answers to your most-asked SPF questions. What’s myth and what’s true? Let’s find out.

 Two hands, one on the left with darker skin and one on the right with lighter skin, hold bottles of The Ordinary UV Filters SPF 45 Serum.

What is SPF?

SPF stands for Sun Protection Factor, and simply put: it’s a rating that measures how much UV radiation is needed to cause a sunburn.

 

More specifically, SPF ratings measure sunburn-causing UVB rays. The SPF number we see is determined by how much exposure to UVB rays it takes to burn skin that has sunscreen applied to it, versus skin that doesn’t.

How is SPF Calculated?

SPF ratings are calculated by dividing the time that it takes for skin to turn red when exposed to UV with sunscreen, by the time it takes to achieve the same without sunscreen—or the medium erythemal dose (MED).

Does higher SPF Equal More Protection?

Not by much, according to science.

SPF values aren’t linear. In fact, SPF 50 only offers an additional 1% of protection against UVB rays vs. SPF 30. Not a huge difference, right?


Here’s what to remember about SPF ratings:
SPF only measures protection against UVB rays
Higher SPF ratings don’t necessarily equal better protection
Broad-spectrum protection is key

Why?
UVA protection should also be considered as well as UVB, since these rays are responsible for signs of aging due to sun (or “photoging”)

Two models apply The Ordinary UV Filters SPF 45 Serum to their faces, demonstrating its easy application for daily sun protection.

Is Mineral Sunscreen Better Than Chemical?

This is definitely a myth. Mineral and chemical sunscreens do use different methods to protect your skin from UV rays, but one isn’t necessarily better than the other.

Chemical sunscreens use organic or “chemical” UV filters that are carbon-based molecules.

  • They absorb harmful UV radiation and convert it 
  • To harmless energy, primarily heat

How this works: These molecules contain electrons that absorb UV light, become excited, and release energy to return to a stable state, repeating this process to protect the skin.

Mineral sunscreens use inorganic or “mineral” UV filters, such as zinc oxide and titanium dioxide, and lack carbon atoms.

  • They absorb UV radiation and scatter it 
  • Scattering about 5-10% of UV rays

How this works: Their unique band-gap structure allows them to absorb a wide range of UV light, releasing energy as heat or lower-energy light.

Why We Went Chemical

We chose to formulate UV Filters SPF 45 Serum with chemical filters because while both chemical and mineral filters can be used in a formulation to provide great UV protection, it is harder to formulate a truly transparent, lightweight, and accessibly-priced sunscreen with mineral filters alone.

So we worked with a blend of FDA-approved chemical filters to formulate a lightweight, broad-spectrum sunscreen that feels comfortable on the skin.

How Much SPF Do You Need to Apply?

We recommend applying UV Filters SPF 45 Serum liberally as directed to the face and neck, as the last step of your daily A.M. skincare regimen.

What About the Two-Finger Rule for Sunscreen?

Some people use the two-finger rule to apply their sun protection, whereby they use two finger-lengths of product to cover their face and neck. However, this method may be interpreted differently by different people, so it's not necessarily a consistent way to measure. Additionally, different countries will have different recommendations based on their local healthcare authorities and organizations. For this reason, we always recommend applying liberally and reapplying as needed.

Do Deep Skin Tones Need to Apply Sunscreen?

Of course! It is always advisable for deeper skin tones to apply sun protection daily.

Deeper skin tones are much more prone to the development of hyperpigmentation, and this is actually exacerbated by UV exposure.

And while research shows that melanin present in deeper skin tones does indeed provide an intrinsic SPF (in the region of SPF 13 for Fitzpatrick types V to VI, according to one study), there is still a lot of UV radiation that can get through this natural protection.

UV Filters SPF 45 Serum is formulated without a white cast, and goes on like a lightweight serum, leaving your skin looking hydrated and luminous.

Clearing Up Sunscreen Questions: Your Daily SPF Guide

Sunscreen can spark a lot of questions, but understanding the science behind SPF is key to effective sun protection. We've explored what SPF truly means, why higher numbers aren't always vastly different in protection, and how both chemical and mineral filters effectively shield your skin. Most importantly, we've busted myths, making it clear that everyone, including those with deeper skin tones, needs daily sun protection to prevent issues like hyperpigmentation.

Our UV Filters SPF 45 Serum was specifically formulated with FDA-approved chemical filters for a lightweight, transparent feel, making daily application easy. Remember, achieving its full broad-spectrum protection relies on applying liberally as directed and consistent reapplication throughout the day. This commitment safeguards your skin against UV radiation and supports its overall health.

UV Filters SPF 45 Serum