Steven Chang, MD

The Best Sun Protection Plan for Rain or Shine


Q What does SPF mean? Does a higher SPF mean better sun protection?

A SPF stands for Sun Protection Factor and refers to the theoretical amount of time you can stay in the sun without getting sunburned. For example, an SPF of 15 would allow you to stay in the sun 15 times longer than you could without protection. So, if your skin starts to redden in 20 minutes without sun block, applying a product with SPF15 increases that time by a factor of 15, meaning you could stay in the sun for 300 minutes. In addition, a higher SPF blocks out more rays–a product with an SPF of 15 will filter out approximately 93% of UVB rays; SPF 30 filters out about 97%.

But in reality, it’s not quite so straightforward. A multitude of factors affect how well you are protected from the sun. Sunscreen can be easily washed off by exposure to water or sweat, which can leave parts of your skin vulnerable to UV rays. Applying your sun protection unevenly or not reapplying sunscreen often enough can also reduce its effectiveness. Even your genetic make-up comes into play. If you have fair skin or if there is a history of skin cancer in your family, you may be at higher risk for skin cancer. Finally, certain medications–such as antibiotics or products with retinol–can make your skin more sensitive to the effects of sunlight.

It’s also important to know that SPF only applies to UVB rays. There is no SPF equivalent for UVA. You can look for additional ingredients in your sunscreen to protect you from UVA–such as zinc oxide and titanium dioxide–but there’s no standard measurement for how long these ingredients will keep you protected.

For all of these reasons, it’s not a good idea to solely rely on SPF to gauge how much time you can spend in the sun. For most people, SPF 15 will suffice, if you keep in mind the following tips:

Select the Right Sunscreen

Choose a sunscreen that protects against both UVA and UVB. Look for products containing zinc oxide or titanium dioxide because they protect against the full spectrum of UVA rays.

Lotion Up Liberally

Reapply sunscreen at least every two hours–sooner if you swim or exercise because water, sweat, and clothing can remove it from the skin. Don’t skimp! You should use at least an ounce with every application, so in a full day at the beach you’d go through half of an eight ounce bottle.

Try Sun-Protective Clothing

Choose your clothes wisely before you go out in the sun. Dark clothing can block nearly all UV radiation and tightly woven fabrics are more protective than looser weaves. If you’re wondering how well your clothing will protect you, just hold it up to the sun. If you can see light passing through it, UV rays can get through, too.

You might also consider purchasing special sun-protective clothing. A relatively new rating for sun protective textiles is UPF, or Ultraviolet Protection Factor. UPF blocks both UVA and UVB rays. (You can find UPF-rated clothes online at

Special laundry detergents such as Rit Sun guard ( can increase the UPF of most clothing for about 20 washings. Keep in mind that no matter what you’re wearing, all fabrics block less UV light when they’re stretched or wet.

Check Yourself

Keep an eye on your skin: Look for new moles or changes in old moles and report any concerns to your health care provider. We recommend annual skin exams for anyone over 40, or for anyone with fair skin or a history of multiple sunburns.

For more information on how to stay safe in the sun, check out and the American Cancer Society.

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  1. tiras harris says:

    Im trying to find a rating for sunscreen

  2. pooja kundu says:

    sir i hav a medium complection and few spots which cums and goes with tyms so cud u suggest me any tips to remove it permently and get a clear and fairer skin and i also hav a big dark spot in my back so any solution for dt.dt z nt a sun burn and my hands colour z different frm my arms so wat i should do make it all d same throughout…..pls sir help me out wid ur suggessions i will b grateful thanku……..

  3. JOY says:

    Hi. I would like to find out if we apply too high of SPF, will it block the pore? The skin will look no energy at all.

    Please advice. Thank you

    • Hi Joy,

      Thanks for your question. Some sunscreens can presumably block your pores, but it’s the nature of the sunscreen itself and not the SPF that is the determining factor (e.g. thick sunscreens may clog more than thin ones). Even the lotions with the highest SPF will not block all the sun’s rays, but certain clothing can. In most cases, your skin will be much happier out of the sun than in it. The one thing we need from sun exposure is vitamin D, but you can also get that through diet or supplements.

      Malcolm Thaler, M.D.
      Clinical Editor
      One Medical Group

  4. dana says:

    im confused I don’t want any sun do I use a higher number like spf 125 or a low number such as 15 I don’t want my face any darker.but the rest of me can burn. Help me somebody.

    • Hi Dana,

      If you’d like the maximum sun protection, use a high SPF sunscreen. I’d recommend choosing between SPF 30-50. Anything higher than SPF 50 has no substantial incremental benefit (based on chemistry limitations). The best protection is to stay in the shade, wear a hat and long sleeve clothing to prevent direct exposure to sunlight.

      Malcolm Thaler, M.D.
      Clinical Editor
      One Medical Group

  5. Rajnish Tandon says:

    This is a good post. This post gives truly quality information. I’m definitely going to look into it. Thank you so much. Keep up the good works…

  6. Md.ahmad ansari says:

    How is use!
    Sun block

  7. jophin says:

    sir, is there any need to use sunscreens in a cloudy day?

  8. Sylvia Stantzos says:

    Hello I have a question about my daughter she is three and a half years old and I take her to the pool in the afternoon always after 3 o’clock I always use UVA UVB protection broad spectrum SPF 50 plus on her she is very fair skinned and I definitely want to protect her skin my concern is I always try to wear a Sun Hat on her but the other day she took her
    Sun hat off and I had her hair in pony tails and her scalp got a little bit pink so my concern is what can I do for her scalp if she will not wear a Sun Hat I want my daughter to be able to enjoy the summer and going into the pool I’m just really concerned because I had a friend who died in her early 20′s from skin cancer on her scalp/head I think it was from sunburns over the years growing up I do not want to live in fear but I also want to protect my child and our skin can you please help me and give me some advice thank you very much!!

  9. heather says:

    if u have dark brown skin what spf should be use.

    • Hey Heather,

      Thanks for your question! For the best protection, look for sunscreens with an SPF of 30+ with both UVA/UVB ray protection. This applies for everyone regardless of his/her skin tone.

  10. athulya says:

    can i apply any cream or powder after apply the sunscreen lotion??and Is LAKME SPF 24 is a good one or not?pls reply me..

  11. Emmir Azmeer says:

    hi..i’m using a sunblock with spf of we know, it can last of 650 minutes under the sun without burning sensation…650 minutes= 10 hours ++..
    do i need to reapply every 2 hours of that sunblock?
    why we need to do so since my sunblock can last of 10 hours??

    • Hi Emmir,

      Please see above in the section “lotion up liberally”: We suggest reapplying sunscreen about every two hours. Many contributing factors throughout the day can reduce your protection, so reapplying every so often ensures you’re properly covered.

      Also note Malcolm Thaler, MD’s comment to Dana: Anything higher than SPF 50 has no substantial benefit–SPF 30-50 should do the job.

  12. tanya says:

    My skin is fair ihad dark spot .i use olay 24spf after few mintue i aply my face olay white ist good for me

  13. Tom Hama says:

    My skin is pale like marks an

  14. Abdullah says:

    Hello. I am having Acne vulgaris on my face and my dermatologist suggested me a sunscreen lotion (Zinc Oxide lotion) ‘SPF 30′.I want to know that does it work for acne too? if yes then how?

  15. Alejandra says:


    My question is, if sunblock with SPF higher than 50 has no substantial benefit than why are there so many brands out there making higher SPF sunblocks? For example: SPF70,85,100.

    • Thanks for your note, Alejandra. To simply answer this, it’s because there’s a general belief in our society that “more is better.” The benefits gained by increasing the SPF beyond 30 are extremely small, which is why we suggest a minimum of SPF 30.

      Malcolm Thaler, MD
      Clinical Editor
      One Medical Group

  16. sam says:

    Please tell me spf20 is better or spf 30 better

  17. Bryan says:

    Does the SPF matter or it just counts as how long it protects you from the sun ?

  18. preeti sharma says:

    Sir if we use more SPF like not SPF 15 but if we use spf50 or more then there is any advantage of using more SPF

  19. jack says:

    i use joy spf 25 is it better?

  20. aditya says:

    I am using lakme SPF 24 fairness + UV protection sunscreen is it ok???? I want to get a fair skin help.

  21. prince saini says:

    Sir can u tell us regarding which lotion should we use..?

  22. Pamela Moore says:

    I find it very hard to believe you need to use as much sunscreen as recommended. This seems to be a recent fad brought on perhaps by the sunscreen industry. I cannot imagine using that much sunscreen everyday. You would need to take out a second mortgage on your home to spend that much money on sunscreen every month. At 70 years old, I so far have not encountered any skin problems even though I only apply it once a day and many friends do not apply it at all, and I know no one who has skin cancer. I realize the atmosphere is probably different than in the last 70 years and, according to news reports, skin cancer is on the rise. However, I also believe some of the hype is brought on by the eternal greed of the American business community to grow the bottom line regardless of truth or any financial difficulty it may cause the public.

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