How Much SPF Do You Need in Your Sunscreen?

How Much SPF Do You Need in Your Sunscreen?

How Much SPF Do You Need in Your Sunscreen?Some great articles on IMBB get lost amongst the horde of articles here. Months ago, SRV wrote an article on ‘Ingredients in Cosmetics and Beauty Products: The Real Story‘ which was an eye opener for me and really got me thinking. One big question that came into my mind at that time was ‘How do these companies decide SPF of their product?’ to put on the labels of their product? Or more importantly, since SRV said that most India companies stick these SPF numbers on their products randomly, what IS the correct procedure for determining SPF in cosmetic products or sunscreen? Also, what would be the correct sunscreen to pick?

To avoid the crime of repeating myself, I would request the readers to read my article on sunscreen first to know some facts about sunscreens. Also read the description of Fitzpatrick Skin Type to understand the basic skin type used by scientists/ dermatologis in determining the spf.

For continuity, I am posting the basic information about SPF that I wrote earlier:

What is SPF?

Sun Protection Factor (SPF) is a measure of a sunscreen ability to protect against the UVB rays, the rays that cause sunburn. The SPF is the amount of UV radiation required to cause sunburn on skin with the sunscreen on, relative to the amount required without the sunscreen. So, wearing a sunscreen with SPF 15, your skin will not burn until it has been exposed to 15 times the amount of solar energy that would normally cause it to burn. That means that it has cut down the radiation to 1/15 of the original or blocked 14/15 or 93% of UVB rays. Using the same logic SPF 30 stops (1 – 1/30) or 97 percent of UVB rays. If you go as high as SPF 50 it stops 98 percent of UVB rays. But no matter how high the SPF, it is only a protection against UVB, and NOT the UVA.

How to Determine SPF of a Product/ Sunscreen?

To calculate SPF, scientists gather 20 human volunteers who are especially susceptible to sunburn. According to FDA guidelines, volunteers must have a skin type of I, II, or III on the Fitzpatrick phototyping scale. Using a device called a “solar simulator,” experimenters irradiate a small patch of skin on each subject and then record the UV dose required to produce mild redness (in scientific parlance, the “minimal erythematic dose”). After applying a thick layer of sunscreen, the experimenters repeat the test. Then they divide the MED needed to redden the protected skin by the MED needed to redden bare skin. The result, rounded down to the nearest five, is the SPF.

How Much SPF Do You Need in Your Sunscreen?

Very simple if you think of it. All you need to know is your Fitzpatrick skin type. Your Fitzpatrick skin type determines how long you can stay in the sun without any sunscreen. Here is a rough guideline on how long can you stay out in the sun without sunscreen-

Skin Type 1: 20 minutes
Skin Type 2: 30 minutes
Skin Type 3: 40 minutes
Skin Type 4: 60- 90
Skin Type 5: About 120 minutes
Skin Type 6: For many many hours

rati beauty ad

Now all you need to know is how long are you going to stay out in the sun for a particular day and divide it by the number of minutes you can stay in the sun without the sunscreen for your skin type and you get your SPF number. So for example, if you are skin type 2 and you need 10 hours or 600 minutes of protection in the sun you need an SPF of 300/ 30 = 10. If you need 24 hours (1440 minutes) of protection for skin type 2, you need an SPF of 1440/30 = 48 or around 50.

Conversely, if you are skin type 1 and you are using an SPF of 15, you can stay out in the sun for 20 x 15 = 300 minutes (5 hours). After that you would need to reapply your sunscreen if you want to stay out in the sun further.

Remember that these figures would not work if you are going for swimming or such similar activities. If you go for a swim, remember to apply the sunscreen again after you have toweled off.

Sun Protection through Clothing

The following are SPF’s of various types of clothing:
Nylon Stockings- SPF 2
Hats- SPF 3-6
Summer-weight clothing- SPF 6.5
Sun-protective clothing- up to SPF 30

T-shirts and most summer weight fabrics allow as much as 50% of harmful UV rays through to your skin when dry and 60 to 70% when wet. T-Shirts provide only moderate protection. In general, heavier, darker, more tightly woven fabrics like denim offer more sun protection than lightweight fabrics like linen and lace. Hats that cover the head and neck offer great protection. Wide rims that go all the way around are the best. Open mesh baseball caps and open-weave straw hats don’t offer good sun protection because they allow UV rays in.

What is the Best Sunscreen Available?

As I mentioned in my earlier article, most sunscreens provide protection against the UVB rays of the sun and not the UVA rays. UVA radiation reaches deeper into the skin and contributes to wrinkles and skin cancer risk. Nearly all (95%) of the UV radiation that we are exposed to is UVA radiation. The best UVA protection is provided by products that contain avobenzone, and ecamsule. But these compounds quickly go photodegradation in the sun, breaking down and losing effectiveness fast. A chemical stabilizer is included in some sunscreens containing avobenzone to slow its breakdown – examples include formulations containing Helioplex and AvoTriplex.

So if you are looking for a good sunscreen for both UVA and UVB protection look for the following products- avobenzone, meroxyl, ecamsule, helioplex, micronic zinc oxides.

Some Sunscreen Suggestion

Neutrogena sunscreens with Helioplex
La Roche-Posay with anthelios, meroxyl.

Hope this article helps you understand SPF and sunscreen better. πŸ™‚

Images: 1, 2

How Do They Measure SPF?
High-SPF Sunscreens: Are They Better?


28 thoughts on “How Much SPF Do You Need in Your Sunscreen?

  1. I have used sunscreens from spf 15 to spf 50..and honestly saying,I do not see any much difference at the end of the day .
    Infact I am using this current sunscreen ,not because it has high spf but because it helps my skin stay oil free for long 😐
    I have a friend who does use sunscreen at all,and she never gets tanned :struggle: :struggle: :struggle:

    1. Ritika, umm… how would you tell the difference between spf 15 and 50 by the way? I mean, what is the difference that you expect would show? πŸ™‚

      Can’t say about your friend or what she uses..maybe she uses some other product which has some SPF in it, or that she doesn’t stay out in the sun for long.

      1. I am not sure either . Infact I higly doubt some . I found this fake Loreal product in the market the other day ,which claimed to have spf 99 !
        And the only way,I can determine the difference between an spf 15 and an spf 50 sunscreen is the ‘feel good’ factor . I dont know if you can understand ,but the higher spf sunscreens I have used have all this great feeling on the skin :toothygrin: :toothygrin: :toothygrin:
        There have been times when I just used Lacto calamine and went out in the sun,it contains Zinc oxide too and I personally feel its pretty good

  2. Sunscreen or not i always get tanned/burned under harsh sun ,in chennai(worked there for 2 years). i always drap my face with a cotton duppatta and wear glares ..Most of friends call me terrorist when they see me like that :silly: …but its the only effective solution i have against tan and burns when travelling by car/bus.Like that my face doesnt sweat too much and feel fresh when i reach my destnation.:)

  3. Thats a nice article Sanjeev, :thanks: the sunscreen that I use has both UVA and UVB protection. Had sent you an article on that but haven’t seen it here yet. anyways, since my skin is prone to sunburns very easily, like even if I go out in the sun for 10 mins, one can clearly make out the amount of tanning, so I think I am Fitzpatrick skin type 1, so a sunscreen with SPF 35 and above only works for me. And I have to reapply otherwise after 2 hrs or so, the effect starts wearing off..Fair skinned people are less prone to tanning, since they already have lower amounts of melanocytes that produce melanin in their skin, and tanning happens when melanin production is triggered by UVA rays and since medium to dark skinned people have more melanocytes, they produce more melanin and eventually tan more than others. Maybe that explains certain cases….

  4. I get burnt very easily too.. And this was a very informative article. Thanks for posting this!
    Thanks to IMBB, I currently use the Neutrogena spf 50 one. It has now become my HG. And for me, an spf of minimum 30 is a must.

  5. very helpful info there, thanx!

    Unfortunately, as the owner of the acne-prone skin, I have to choose between acne and tanning, and i end up choosing tanning. I have observed that higher the SPF, worse is my acne. Fighting with clogged pores and acne is more disturbing than worrying about a lil darker skintone.
    Atleast tanning can be tackled by staying indoors over d w/end and applying few packs.
    But I try to use SPF over 30 and PA++.

    Since they r related, it wud b nice if u cud dig up some info on PA and the ++++ after it?
    :yes: :thanks:

  6. very informative post sanjeev…. :waytogo: :waytogo: :waytogo:
    u knw d dermo, me took Rauni to, he told us not to use sunscreens, it will clog pores n thus b breakouts … n both of u s were 😐 😐 😐 😐 😐 😐 😐 😐 😐 😐 😐 😐
    he just said carry umbrellla wen outdoors

      1. waise naa, even i hav noticed tht this yr i didnt use sunscreen at all,n i dint get that bad acne attack i always get in summers 😐 😐 😐

        haan waisi 1 chatri – black thickkeshtt cloth n wid pointed top hai hamare ghar pe…. daada ji ki chatri :yahoo: :yahoo: :yahoo: :yahoo:

    1. Thats true Nupur..even my Derma suggested not to use sunscreen becoz it will clog pores and I was like WHAT?? dont we have sunscreens which donot clog pores and she asked me to use Lacto Calamine lotion only 😯

      1. same with me Pari. My dermo asked me to use lacto calamine in stead of sunscreens. and i actually think it works better that some of the sunscreens i’ve used. but i still use sunscreen when i need to step out for long. :struggle:

  7. I think I am skin type 1……didn’t know about all these Sanjeevji….thanks for the info :waytogo: :waytogo: :waytogo: :waytogo: :waytogo: :waytogo: :waytogo: :waytogo: :waytogo: :waytogo:

    1. My brother has the same problem. 😐 My migraines are almost always triggered by loud noises and hot and dry weather. :yikes:

  8. I’m type 4. πŸ˜₯ And this article has made me go from :whistle: to :shocked: because a substantial amount of the info here have never come my way. 😐
    :thanks: so much,Sanjeev ji!
    And honestly,I’ve never understood this whole SPF whatchamacallit. 😐 So now I’ll be more careful! :zombiekiller:

  9. hmm my skin type in type three….i do get tanned very easily…..but i also develop small boils or rather i dun know what u call them…….and get tons of uneven skintone…… :headbang: :headbang: .i have tried so many sunscreen but none of them worked.the only thing halped me was vaseline healty white.i now i swear by it……….. :high5: ….i went camping in the snow.and still my skin was cute as ever……..but bloddy the new vaseline healthy white with spf 24…….is so bad.i applied it on my face and found that bleacy sensation.and no good results…. :spank: :spank: :spank: .thank god itook a small bottle……….. :specs:

  10. My first time here. Quite love the content . Have been browsing through the blog and enjoying it for some time. Never got to leaving a comment though.

    I have to say this. I don’t trust the SPF values claimed by brands. I had been to a beach holiday and religiously used a sunscreen with SPF 50..It just did not help. I got badly tanned..

  11. Great article! I’ve been a little wary of this SPF hocus-pocus ever since I realised that my SPF 50 sunblock could stop neither skin tanning nor a minor sunburn on a beach holiday. I have used Lacto Calamine all summer because I don’t stay out in the sun for too long anyway and my skin has been virtually tan-free and pretty normal even though I am a Type 3.

  12. Nice article…seriously sunscreens hardly help…they make u look like havng bad tan for so long..u need to reapply cz it generates free radicals.which cause the s better to lessen the exposure to sun n use other protective measures..

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