how much sunscreen do you need to use?

How much sunscreen should you be using on your face and body every day to keep your skin safe from UV harm? I used to think that a high SPF was enough. As long as I slather on SPF 30 or higher, it doesn’t matter how much I apply, it’s going to keep my skin well-protected even in the scorching hot summer months. Boy, how wrong I was!

It doesn’t matter how high your SPF is, quantity matters too. Don’t get me wrong, of course you do want a high SPF. Anything under 30 is pretty much useless. BUT, here’s the catch: you could slather on SPF 100, but if you skimp on application because the texture’s all greasy and unpleasant, it’s not going to protect your skin as well as you think. And then you wonder why you got a sunburn even though you were so careful!

It’s not the sunscreen’s fault. And frankly, it’s not your fault either. Everyone is telling you to apply sunscreen liberally but, realistically, how much is that?! A thick layer? Half a teaspoon? You do a quick Google search and everyone has a different answer…. I’ve talked to lots of dermatologists over the years and here’s how the answer the question, “How much sunscreen should you apply on your face and body every day?” Let’s find out:

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How Much Sunscreen Do You Really Need To Use For Your Face?

Did you know there’s a difference between the way scientists test sunscreen efficacy and the way people use sunscreen in daily life?

“To get the protection labeled on the product, you would need to replicate the application they do in the lab, which is 2 milligrams per square centimeter for the average person. That translates to half a teaspoon on face and neck combined — a quarter teaspoon each” says board-certified dermatologist Ranella Hirsch. “Realistically, people use somewhere around half of that amount.”

 If that’s too complicated to remember, here’s some practical advice from board-certified dermatologist Marisa Garshick: “For the face, it is recommended to apply a nickel-sized dollop — the equivalent of two finger lengths, which is also equivalent to half a teaspoon, to the face and neck combined.” It doesn’t matter if you’re using a chemical or physical sunscreen, by the way. Always apply exactly this amount.

But what if you’re using a stick sunscreen? I’m not a fan, but if you must use one, “apply four passes back and forth and then rub it in after for even coverage,” Garshick says. What about sprays? I do NOT recommend at all. They’re see-through, so it’s impossible to see if you’ve skipped a bit of skin. But, if you insist on using them, apply them until there’s a visible sheen on the skin (you must make sure every inch of skin is covered!).

How Much Sunscreen Do You Need For Your Body?

You still need to apply 2mg per cm2 as that’s how scientists test the efficacy of your sunscreen. But how much is that for your body? When you go to the beach, you just want to slather sunscreen on, not do math equations in your head, know what I mean?

2mg per cm2 translates to 1 teaspoon per arm and leg each, front and back,” says Hirsch. What about the whole body? This time Garshick comes to the rescue, explaining that’s “equivalent to one shot glass for the body or two tablespoons.”


Here’s how much 2mg per cm2 is in real life:

  • Face only: 1/4 of teaspoon
  • Face and neck: 1/2 of teaspoon
  • Arms: 1 teaspoon each
  • Entire body: a shot glass

WARNING! These are general guidelines. If you have a bigger than average face, you’ll need a bit more. If you have a smaller face, you’ll need a little less.

Related: Are You Applying Sunscreen The Right Way?

How Much SPF Do You Get If You Apply Less?

Rumour had it, if you apply half the amount of sunscreen you need to stay safe in the sun, you’d get the protection of only the square root of the SPF. So a SPF 70 turns into a SPF 8.4! Scientists calculated it with the Beer-Lambert law, a physics law that says that protection decreases exponentially with less sunscreen. Michelle of Lab Muffin has a great post about this, if you’re interested in the science behind this law.

But, I’ll keep this simple for you. Scientists used this law to theoretically judge how much application affected SPF. Until one day, someone, somewhere, decided to put this law to the test. You know what they found out? The latest research shows that, with less application, SPF decreases linearly, not exponentially.

In other words, applying half the recommended amount gives you half the SPF. So a SPF 50 becomes a SPF 25. That’s more like it, isn’t it? But don’t go using this excuse to apply less sunscreen now. What’s the point of buying SPF 50 if you don’t get the full protection out of it?

Best Sunscreen Picks

Not sure which sunscreens to use? Here are my fave sunscreens for every skin type and need:

  • Drunk Elephant Umbra Tinte Physical Daily Defense SPF 30 ($36.00): A tinted mineral sunscreen that protects you from all UV rays without leaving a white cast behind. Best suitable for dry skin. Available at BootsCult BeautySpaceNK, and Ulta.
  • La Roche Posay Anthelios Clear Skin Dry Touch Face Sunscreen SPF 60 ($19.99): Ideal for oily skin, this lightweight sunscreen provides broad spectrum protection and absorbs excess oil for a matte finish. Available at BootsDermstoreLa Roche Posay, and Ulta.
  • Paula’s Choice Defense Essential Glow Moisturiser SPF30 ($26.40): Suitable for all skin types, this tinted mineral sunscreen provides broad spectrum protection, fights premature wrinkles, and dries to a luminous finish. Available at Cult BeautyPaula’s ChoiceSephoraSelfridges, and SpaceNK.
  • Shiseido Ultimate Sun Protection Lotion Broad Spectrum SPF 50+ WetForce for Sensitive Skin and Children ($42.00): A high SPF, broad spectrum protection formula that’s gentle enough even for children and sensitive skin. It’s water-resistant for up to 80 minutes. Available at Sephora and Ulta.
  • Supergoop! Mineral Mattescreen SPF 40 ($38.00): A mineral sunscreen that provides broad-spectrum protection and dries to a silky matte finish. It also minimises the look o pores. It’s best suitable for oily and combination skin. Available at Blue MercuryNordstromRevolve, and Ulta.
  • Ultrasun Ultra Sensitive Very High SPF50+ Extreme Formula (£30.00): This sunscreen uses the new generation of chemical filters to provide broad spectrum protection without the irritation. Suitable for sensitive skin too. Available at BootsSephora, and SpacenK.

The Bottom Line

If you want the protection the SPF promises you, you need to apply sunscreen in the same way researchers test it to determine that SPF in the first place. Put simply, you need to use 1/2 of teaspoon for your face and neck and a shot glass for your entire body.