Style and Beauty

What does SPF mean?

Make sure you know the ins and outs of sunscreen to keep your family safe this summer.

By Lia Grainger
What does SPF mean?

What does SPF mean?


All sunscreens list a sun protection factor (SPF) on their labels, and in recent years, these numbers have climbed as high as 100, prompting many to question exactly what they mean.

Here’s the lowdown so you're ready for summer.

Also read: Family sunscreen safety>

A version of this article appeared in our June 2013 issue with the headline "Family suncare essentials," pp. 36-38.

What does SPF mean?Photo: markokg/iStockphoto

When to reapply

No matter how high the SPF, sunscreen needs to be reapplied at least every two hours to be effective — sweating and movement can cause it to slough off or absorb into the skin, rendering the SPF meaningless.

What does SPF mean?Photo: malhrovitz/iStockphoto



SPF only refers to UVB rays. To ensure UVA protection, make sure your sunscreen is labelled "broad spectrum."

What does SPF mean?Photo: casara/iStockphoto

SPF 100

SPF 100 sunscreen protects from 99 percent of UVB rays, while SPF 30 protects from 96.7 percent — not a big difference. The Canadian Cancer Society recommends a minimum SPF of 30.

What does SPF mean?Photo: madisonwi/iStockphoto

Apply generously

Proper application of sunscreen — generously, every two hours — is as important as the lotion’s SPF.

What does SPF mean?Photo: mango/iStockphoto


Our fave sunscreens for summer

What does SPF mean?

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