What is SPF and its importance?

SPF full form is Sun-protection-factor. SPF meaning or sun protection factor meaning is the amount of protection provided to our skin from the unwanted harmful rays of the sun. 

Everyone must have used sunscreen in their life, and if you haven’t then you should use it now. To enjoy the outings freely without any fear of harmful sun rays; UVA, UVB, IR and also pollution you should be using a broad spectrum sunscreen with good Sun Protection Factor (SPF).

Sunscreen will protect your skin from sunburns, suntans, photo-ageing, dull complexion, skin inflammation and even skin cancer in more severe cases. Sunscreen For Face has a number written as Sun Protection Factor, i.e. SPF 15, 20, 30 or 50 on the pack. Have you ever wondered what does it mean and what is its significance?

Let's understand

Sunscreens are formulated on the basis of scientific calculations known as Sun Protection Factor which is the measure of the protection offered by a sunscreen from harmful UV-B rays. Most of the sunscreens have mentioned this number on the pack. 

Let's watch a short video on SPF:

In this article, we will cover:

1. What are the types of SPF?

2. Whats is SPF 30?

3. Whats is SPF 50?

4. SPF 30 VS SPF 50

5. What is pa+++ in sunscreen?

6. Is it bad to use high SPF?

7. When to re-apply the sunscreen? 

What are the types of SPF?

There are three types of SPF-

  • Physical or mineral SPF- It forms a layer on the skin and blocks the UV rays from entering our skin.
  • Chemical SPF- It sinks into the skin and absorbs UV rays. It appears thin and less greasy on the skin.
  • Broad spectrum SPF- It implies that this spf protects your skin from both UV-A and UV-B rays. A regular sunscreen just protects you from UV-B rays but a broad spectrum gel based sunscreen is ideal and protects you from all types of UV rays.

What is SPF 30? 

It is considered that if your skin normally burns after 10 minutes, then applying a sun protection factor of 30 sunscreens would allow you to stay in the sun without burning for approximately 300 minutes. This is a rough estimate which depends on the type of skin, the intensity of sunlight and amount and type of sunscreen applied.

However, the sun protection factor curve is not linear-

  • SPF15 blocks 93% of UV-B rays
  • SPF30 blocks 97% of UV-B rays
  • SPF50 blocks 98% of UV-B rays ( Hence, the best SPF)

Another way of understanding is that we can consider that SPF15 only allows 7 photons out of 100  to enter our skin and in the same way SPF30 allows only 3 photons out of 100 to enter our skin. Thus it gives 4% times longer protection than sun protection 15.

What is 50?

It means that this blocks 98% of the UV rays from entering the skin and thus preventing skin cancer and various other skin related disorders.

How long does spf 50 last?

Sunscreens with sun protection 50 approximately last for 500 mins, if your skin burns normally in 10 mins in the sun. Thus, 50x times the duration your skin takes to burn out.

SPF 30 vs 50 difference


The only minute difference between these two is that sun protection factor 50 provides more protection than sun protection factor 30. Thus it can be said that SPF50 is the correct spf to use.

The Sun Protection Factor also tells about the time at which the sunscreen needs to be applied again.

What is pa+++ in sunscreen?

No doubt a high Sun Protection Factor can protect your skin from sunburn-causing UVB rays, but your skin also needs UVA protection. 

The protection grade of UVA rays is denoted by PA in the sunscreen. PA is levelled by PA+, PA++, PA+++; the more the plus signs, the more is the protection from UVA rays.

Is it bad to use high SPF?

It's not recommended to use the highest SPF sunscreens like SPF 75 or SPF 100 because higher SPF do not provide more protection than SPF50 and mislead people. In order to achieve broad-spectrum protection, UV-A protection should be at least one third that of UV-B. Thus never consider that high spf sunscreens are better. It is important that you choose sunscreen according to your skin type.

When to re-apply the sunscreen? 

If you are exposed to the sun and pollution for a longer duration then you need to re-apply your sunscreen. Sun protection factor wise reapplying time is mentioned below:

Sun Protection Factor

Time to re-apply the sunscreen



After 1 hour


After 2 hours


After 4 hours


After 6 hours

These days not only the UV rays but IR rays and Urban Pollution have become the concern for the skin. So, you should buy a sunscreen which offers you protection against all of these harmful environmental factors. 

There are a few sunscreen brands on the market which offer complete protection, one of the best sunscreens is the Derma Essentia SPF 50, PA+++ Sunscreen Gel. The Gen-next encapsulated ultralight texture sunscreen gel is non-oily, non-tacky & suits normal to oily skin which protects your skin from UVA, UVB, IR & Urban Pollution.

FAQs on Sun Protection Factor:

1. How to check spf of a sunscreen? 

There are various ways by which we can give a SPF check to the sunscreen we are using. These include invitro and in vivo methods.

2. Is moisturizer with spf effective?

Moisturizers with sun protection factor are not that more effective in protecting skin than a layer of sunscreen on the skin.

3. What SPF is best for face?

Sunscreens having spf between 30 to 50 are considered best for the skin.

4. How much spf is enough for Indian skin?

It is considered that sunscreens and lotions having sun protection factor between 15 to 30 is best for Indian skins.

5. Why is spf important? 

Sun protection factor is important because it tells us about the degree of protection provided by our sunscreen from the harmful UV-B rays of the sun.

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