Is SPF 50 much better than SPF 30?

Slightly. SPF 30 filters about 97 percent of UVB and SPF 50 about 98 percent. Applied at the same proper dose the difference is small, and applied thin, both underperform their labels badly.

How much sunscreen should I use on my face?

About a quarter teaspoon for face and neck, or the two-finger rule: a stripe down the index and middle fingers. Most people apply half that, which cuts protection well below the label.

How often should sunscreen be reapplied?

About every two hours during real sun exposure, and after swimming or heavy sweating. For an indoor day, a proper morning application covers you.

What does broad spectrum mean?

The formula protects against UVA as well as UVB. SPF only measures UVB, so broad spectrum is the label that covers the aging rays too. Treat it as non-negotiable.

SPF 30 vs. 50, and How Much to Actually Apply

The number on the bottle gets all the attention, and it’s the least important decision you’ll make in the sunscreen aisle. Here’s what SPF ratings actually mean, why the 30-versus-50 debate is smaller than it looks, and the application rule that matters more than either.

What the numbers mean

SPF measures protection against UVB, the burning rays. The scale is not linear: SPF 30 filters roughly 97 percent of UVB, SPF 50 about 98 percent. That one-point gap is real but small, and no sunscreen blocks 100 percent. An SPF 100 label buys you decimals, not a force field, and it definitely doesn’t buy the all-day immunity people treat it as.

The label to actually require: broad spectrum, which means the formula also covers UVA, the aging rays. A high SPF without broad spectrum is doing half the job.

The number that actually matters: quantity

SPF ratings are measured at a standardized, generous dose that almost nobody applies in real life. Use half the tested amount, and your effective protection drops far below the label, which is how people burn wearing SPF 50. The working rules:

Face and neck: about a quarter teaspoon, or the two-finger rule, a stripe of sunscreen down the length of your index and middle fingers.
Body: about a shot glass worth for full coverage in a swimsuit.

This is why a pleasant texture is a protection feature, not a vanity one. A formula you’ll apply generously, like the ones on our facial sunscreen shortlist, outperforms a higher number you ration.

Reapplication, the other half

Sunscreen wears off with time, sweat, water, and touch. The standard guidance: reapply about every two hours during real sun exposure, and after swimming or sweating regardless of the clock. For an ordinary indoor workday, a morning application does the job. For a beach day, the two-hour rule is the whole game, and reapplying over makeup is solvable without ruining your face.

So which number should you buy?

SPF 30 or higher, broad spectrum, in a texture you’ll apply at full dose every day. Between two formulas you love, take the 50, the margin is free. Between a 50 you ration and a 30 you apply properly, take the 30. The bottle number is a starting condition. Your hand does the protecting.

Frequently asked

Is SPF 50 much better than SPF 30?: Slightly. SPF 30 filters about 97 percent of UVB and SPF 50 about 98 percent. Applied at the same proper dose the difference is small, and applied thin, both underperform their labels badly.
How much sunscreen should I use on my face?: About a quarter teaspoon for face and neck, or the two-finger rule: a stripe down the index and middle fingers. Most people apply half that, which cuts protection well below the label.
How often should sunscreen be reapplied?: About every two hours during real sun exposure, and after swimming or heavy sweating. For an indoor day, a proper morning application covers you.
What does broad spectrum mean?: The formula protects against UVA as well as UVB. SPF only measures UVB, so broad spectrum is the label that covers the aging rays too. Treat it as non-negotiable.