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What Does SPF 30 Mean?

As per its SPF formula, what does SPF 30 mean?

The formula for calculating SPF is =
The time it takes for sunscreen covered skin to burn divided by The time it takes for bare skin to burn

The above SPF formula basically tells you how much protection sunscreen-covered skin offers compared to skin with no sunscreen protection.

So, as per this formula, a sunscreen with SPF 30 means…
A SPF 30 sunscreen offers 30 times more protection than when you had no sunscreen.

But saying 30 times more protection still does not explain what exactly the sunscreen can and can’t do. To understand the 30 in SPF 30 in simple terms, keep reading.

For consumers, what does SPF 30 ‘actually’ mean?

Here is what consumers need to know about SPF 30:

SPF 30 blocks nearly 97% of UVB rays from affecting the skin.
Since it blocks 97% of the sun’s UVB radiation, SPF 30 lets 3% of it enter and affect the skin.
SPF 50 lets 2% of the sun’s UVB radiation enter and affect the skin.
Since SPF 30 lets 3% of UVB enter the skin, in contrast to SPF 50’s 2%, SPF 30 is 50% less effective than SPF 50.

Is SPF 30 ENOUGH?

SPF measures the protection the sunscreen offers from UVB radiation.

But what about protection from UVA??
Remember, we also need protection from the sun’s UVA.

To get protection from both UVA and UVB, use a broad-spectrum sunscreen.

Broad-spectrum sunscreens offer protection against both UVA and UVB.

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How often should we reapply SPF 30?

All sunscreens, irrespective of the SPF number, should be reapplied every 2 hours.

If we don’t apply sunscreen every 2 hours, it’s the same as not wearing any sunscreen.