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  5. What is SPF in Sunscreen? How Does it Work?

Play safe in the sun! If you don’t wear sunscreen, your skin may be at the risk of tanning, premature aging, sunburn and skin cancer. A must-have skincare product, sunscreens protect you from the sun’s UVA and UVB rays.

1. What Is SPF?

SPF or Sun Protection Factor is a measure of how much UV radiation is required to burn your protected skin as compared to the amount required by UV rays to burn your unprotected skin.

For example, if you apply an SPF 30, it will protect your skin until it is exposed to 30 times more UVB radiation than that is required to burn unprotected skin.(1)

For example, if your skin takes 10 minutes to burn normally, a sunscreen with an SPF30 will protect you for 5 hours (10X30 = 300 minutes) from the sun’s rays. However, dermatologists recommend reapplication of sunscreen every two hours.

The rays of the sun are stronger during peak hours - 10 am to 4 pm. Your skin may burn faster at 12 pm as compared to 8 am.

The SPF number also tells us how much percent of the UVB rays the applied product will absorb. A sunscreen with SPF15 will absorb about 93% of the sun’s UVB rays. A sunscreen with SPF30 will absorb about 97%.

The highest amount of UVB rays sunscreens can absorb is 98%. These usually contain SPF50. No sunscreen can absorb 100% of the sun’s UVB rays.

2. How Does SPF Work?

UVB rays tend to damage the epidermis (outer layers of the skin). UVA rays seep into the skin and reach its dermal layers. SPF in sunscreen absorbs or reflects these rays to protect the skin.

3. What Are The Different Types Of SPFs?

A. Physical Or Mineral SPF:

Physical or mineral SPF forms a layer on the skin. They are also called sunblocks because of their ability to block UV rays from entering the skin.

Physical sunscreens are recommended for people with acne-prone skin. They don’t clog pores.

However, they may not be the best option when you’re wearing makeup. They are thick and appear greasy on the skin.

B. Chemical SPF:

Chemical SPF sinks into the skin and absorbs UV rays. They appear thinner and less greasy on the skin.

These are suitable to wear before applying makeup. Chemical sunscreens are also a good option if you have dry skin.

4. What Is Broad-Spectrum SPF?

Broad-Spectrum SPF

A broad-spectrum sunscreen protects you from UVB and UVA rays of the sun

Broad-spectrum SPF implies a sunscreen that protects you from both UVA and UVB rays of the sun. A regular sunscreen protects your skin from UVB rays only.

UVA rays penetrate deep into your skin and may carry the risk of causing skin cancer, tanning and premature aging. Thus, sunscreens labeled “broad-spectrum” are ideal options for daily use.

5. How To Apply Sunscreen?

If you don’t apply your sunscreen properly, your skin will burn.

Sunscreens come in the form of gels, creams and lotions. Whatever you choose, make it a point to apply a thick coat of the product on to your skin. (2) Cover all areas you think will be directly exposed to the sun.

According to dermatologists, you should apply sunscreen 30 minutes before you step-out. Reapply sunscreen every two hours.

Water-resistant sunscreens last for up to 40 minutes. If you love swimming or sweating it out, apply sunscreen 30 minutes prior to your activity. Reapply immediately after finishing your activity.

How Much Sunscreen Should You Apply?

On an average, one ounce (equivalent to a shot glass) should be enough to cover your whole body. (3)

How Often Should You Apply Sunscreen?

Dermatologists recommend applying sunscreen 20 minutes prior to stepping out every time.

If you are outdoors on a daily basis, apply sunscreen everyday 15-30 minutes before leaving your house. Reapply every hour when you’re constantly exposed to the sun. (4)

If you sweat a lot or enjoy swimming on a regular basis, apply water-resistant sunscreen. Re-apply every 40-80 minutes and as soon as you dry yourself up.

What Is The Best Time To Apply Sunscreen?

Ideally, you should apply sunscreen every time you expose your skin to the sun. However, if you’re not a sunscreen person and don’t really enjoy the feel of it, make sure to apply it during peak hours. Peak hours of the sun in India lasts between 10 am and 2 pm. These are the hours when the sun’s rays are the strongest.

Where Should You Apply Sunscreen?

Apply sunscreen on parts of your body that are directly exposed to the sun. This usually includes your face, neck, back, arms and legs. If you’re in the mood to hit the beach or go swimming, preferably apply it on all parts of your body.

6. Who Needs Sunscreen?

A common misconception is that dark skinned people do not require sunscreen. People with dark skin have more melanin. Melanin protects the skin from some amount of UV damage. However, melanin is not effective in protecting the skin from UVA rays (5).

Sunscreen should be worn by everybody. Most people use sunscreen to prevent tan and burns. It is also essential to protect the skin from a range of other skin conditions.

Skin cancer, sun burns, tanning, wrinkles and dehydration can all be the result of direct exposure to the sun. Sunscreen helps prevent these skin conditions.

Babies below six months should not wear sunscreen. They may react to the harsh chemicals of the product. (6) However, the rays of the sun can also damage a baby’s skin. Avoid taking your baby out in the sun before 6 months.

7. Do Sunscreens With High SPF Protect You Better?

Higher numbers always sound better. But when it comes to sunscreens, high SPF numbers do not indicate double protection. For example, a sunscreen with SPF15 protects you from 93% of the sun’s UV rays, while SPF30 protects you from 97%.

Experts worry that people may be misguided into believing high SPF offers extremely high protection. This may encourage people to stay for longer hours in the sun (7).

However, some studies suggest that a sunscreen above SPF70 can offer additional clinical benefits. Research also says that these are more effective than SPF30 or SPF50 sunscreens (8)

8. How To Choose A Sunscreen?

A. Form Of Sunscreen

Sunscreens come in the form of sprays, lotions, gels, creams, butters, sticks, oils and pastes. Choose a sunscreen that you’re comfortable applying.

If you have acne-prone skin, a gel-form would be a good option. If you have young children, a spray would be ideal. If you wear makeup regularly, pick a sunscreen that doesn’t appear greasy. (9)

B. Active Ingredients

Active ingredients in a sunscreen protect you from UVA and UVB rays of the sun. Choose a sunscreen that has suitable and authorized ingredients.

C. Broad-Spectrum

Most sunscreens protect you from UVB rays, which contribute to sunburn and thickening of the skin. UVA rays cause tanning and premature aging. Pick a broad-spectrum sunscreen that will protect you from both the rays. (10) (11)

D. Know Your Skin

Get yourself a sunscreen that suits your skin type and doesn’t interfere with your skin issues.

If your skin is prone to acne, mineral sunscreens are a good option. They prevent clogged pores.

If you have dry skin, chemical sunscreens are ideal.

E. SPF Number

Before you buy a sunscreen, take a look at the SPF number. This will determine how long the sun will protect you for.

If you’re adventurous and love staying out in the day for long hours, buy a sunscreen with a higher SPF number like SPF50! If the only time you’re out in the sun is during your ride from home to office, purchase a sunscreen with a low SPF number.

Dermatologists recommend a sunscreen of at least SPF15 for everybody.

F. Purchase A Water-Resistant Sunscreen

Considering the humidity levels of India, water-resistant sunscreens are a good option.

Your skin expels water through sweat. If you’re particularly active, sweat a lot or spend long hours swimming, choose a water-resistant sunscreen. Re-apply it every 40-80 minutes.

G. Conduct A Patch-Test

Before applying sunscreen on your whole body or face, conduct a patch-test. Look out for any allergic reactions. If your skin feels itchy, red or patchy after applying the product, wash it off and discontinue use. Purchase a sunscreen based on your skin type.

H. Check The Expiry Date

If a sunscreen has crossed its expiry date, don’t buy it. It will not offer the same kind of protection it claims to. Also, make it a point to inform the store manager about this!

9. Do You Get Vitamin D While Wearing Sunscreen?

UVB rays are essential and play a vital role in producing Vitamin D. Some studies suggest that wearing an SPF30 sunscreen or a higher number decreases the Vitamin D production in the body by 95 percent. (13)

A recent study showed that wearing a clinically prescribed sunscreen (SPF15) has a minor impact on Vitamin D production in the body. (14)

It is recommended to wear a sunscreen with SPF15 regularly. Health problems caused by UV rays should be more of a concern than Vitamin D deficiency.

People with a darker skin tone have higher sun protection. However, their body takes more time to produce an adequate amount of Vitamin D. They may be required to stay out under the sun three to five times longer than a white-skinned person.

10. Physical Or Chemical Sunscreen - Which One Is Better?

Physical or Chemical sunscreen

Both physical and chemical sunscreens are effective in protecting your skin. Choose a sunscreen that suits your skin.

A. Physical/Mineral Sunscreens

Pros Of Using Physical/Mineral Sunscreens

  • Ideal for sensitive/acne-prone skin
  • Forms a coat on top of the skin, less likely to clog pores
  • No wait-time is required
  • Offers protection against UVA and UVB rays, naturally broad-spectrum

Cons Of Using Physical/Mineral Sunscreens

  • Not “makeup friendly” as it forms a white coat on top of the skin
  • Constant re-application may be needed as it can rub off easily
  • Has to be applied generously and accurately to offer full protection

B. Chemical Sunscreens

Pros Of Using Chemical Sunscreen

  • Thinner and easy to rub into the skin
  • Works well under makeup and spreads easily on the skin
  • More water-resistant as compared to physical sunscreen
  • Available in ‘broad-spectrum’ to protect skin from UVA and UVB rays

Cons Of Using A Chemical Sunscreen

  • Can clog pores
  • Requires a 15-30 minute wait time before stepping out
  • Can irritate the skin and cause redness
  • Can cause irritation and stinging sensations

Both physical and chemical sunscreens effectively protect your skin against UV rays. Based on your skin type and other preferences, you can decide on what sunscreen you’d like to go for.

11. Sunscreen vs Sunblock: What's The Difference?

A. Sunscreen

A sunscreen penetrates through the skin. Sunscreens are designed to protect the skin against UV rays of the sun.


Sunscreens sink into the skin. It is required for you to rub the product into your skin. Sunscreens may appear greasy, but usually don’t show on the skin.

B. Sunblock

A sunblock doesn’t sink into the skin. It acts as a shield by sitting on top of the skin and reflecting away the sun’s rays. Sunblocks contain zinc oxide or titanium oxide.


Sunblocks appear prominently on the skin. A white coat can usually be seen on the skin after applying the product.

12. Benefits And Potential Risks Of Wearing Sunscreen


  • Protects us from UVA and UVB rays of the sun
  • Allows us to soak up the sun without harming our skin and its appearance, prevents premature aging, burning and tanning
  • Prevents dehydration of the skin

Potential Risks

A. Greasy Appearance

The most annoying part of wearing sunscreen is how it makes our skin look. Spray sunscreens are a good option if you’re out for a day party or event, once in a while.

B. Clogged Pores

Sunscreens can contribute to acne breakouts by clogging your pores. If you have acne-prone skin, pick a physical sunscreen for yourself.

C. Wait Time

Sunscreens should be worn 30 minutes before you step out.

D. Interferes With Vitamin D Production

Some studies suggest that wearing sunscreen can reduce Vitamin D production in the body (15)

Wearing sunscreen can at times frustrate you. But it is an essential product to maintain skin health. Spend time at your cosmetic store, try out different sunscreens to determine their feel and look. Pick one that suits your preference and skin type!

Begin By Knowing Your Skin

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