How to Choose the Right SPF for You

You're headed out for a day of beachin'. You don't mind tan lines, but aren't looking for that lobster look either.

With so many options in the sunblock aisle, what should you use? Is there a perfect SPF that will block harmful rays while letting you enjoy your day in the sun?

A Look at SPF

sunscreen WOC
Flickr/she calls herself molly

Sun Protection Factor measures sunscreen's effectiveness in blocking UVB. What's UVB, you ask?

The sunbeams you soak up include two types of rays. Ultraviolet B rays cause sunburns. Ultraviolet A rays are associated with deeper, more long-term skin damage.

The SPF of your sunscreen tells you how long it should take before those UVB rays get through and start burning your skin. If your unprotected skin normally starts reddening in 20 minutes, for example, applying SPF 15 should protect you for 15 times longer, or about five hours.

Pay attention though. SPF 30 is not necessarily twice as good as SPF 15. What increases with SPF is the percentage of UVB rays that are blocked.

  • SPF 15 = 93% of UVB rays blocked
  • SPF 30 = 97% of UVB rays blocked
  • SPF 50 = 98% of UVB rays blocked

Source: WebMD

These differences in percentages may seem small but do make a difference.

What's the Best SPF?

Anything above SPF 50 really isn't getting you any additional protection from sunburn. No sunscreen offers 100% blockage. You can lather up with SPF 100+ if it makes you feel better; but a small percentage of rays will still sneak through.

SPF 30 should be sufficient for most beach-goers. Apply it 30 minutes before you hit the sun.

Never forget the importance of reapplication. No matter what the SPF of your sunscreen, don't expect it to protect you more than two hours without reapplication. Swimming, sweating and towel drying all decrease the effectiveness of sunscreen. If you're spending a whole day on the dunes, you'll need to reapply regularly. Expect to use a quarter to half of your 8oz tube.

What to Look for on the Bottle

Flickr/Robert S. Donovan

The Skin Cancer Foundation recommends a broad-sprectrum sunscreen - one that offers protection against both UVA and UVB rays. Look for these active ingredients:

  • PABA derivatives
  • Octinoxate and cinoxate for UVB absorption
  • Oxybenzone and sulisobenzone for UVA protection
  • Avobenzone, ecamsule (MexorylTM), titanium dioxide or zinc oxide for the remaining UVA spectrum

Ready For Beachin'

Beach WOC
Flickr/Craig Sunter

When properly applied, a high SPF (15 or greater) combined with broad-spectrum protection will offer you the best defense against harmful radiation. This combination will help you both short and long-term by protecting against sunburn as well as pre-aging and skin cancer.

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How to Choose the Right SPF for You