right way to apply sunscreen

I know you’re applying sunscreen every day. But are you applying it the right way?

Sunscreen ain’t like the other skincare products. Mess it up and it won’t work. So how do you NOT mess it up?

Here are all your questions about sunscreen application answered:

1. How Much Sunscreen Should You Apply?

2 mg per cm2.

That’s the amount scientists use to test sunscreen. But how much is that in plain English?!

Short answer: 1/4 of a teaspoon for your face. A small glass shot for the whole body.

Long answer: everyone’s face is a slightly different size. If your face is smaller than average, you can get away with applying a little less.

Michelle of Lab Muffin, one of my fave beauty science blogs, has done a little experiment, measuring exactly how much sunscreen she should apply. Turns out, she only needs  61% of a teaspoon for her face. You can check out Michelle performing the experiment (and putting tape all over her face) here.

Related: How Much Sunscreen Do You Need To Apply To Get The SPF On The Bottle?

How effective is your sunscreen? Sign up to the newsletter below to receive the “Sunscreen Audit” Worksheet and find out if your sunscreen is really up to the job:

2. What Goes First: Moisturiser Or Sunscreen?

Moisturiser, always. Here’s why:

  1. In studies, sunscreen is always the last product applied to the face – makes sense to use it as they test it.
  2. Touching your face after putting on sunscreen can disturb it, remove it, and generally make it less effective.

Related: In What Order Should You Apply Sunscreen?

3. Can You Mix Sunscreen With Moisturiser?

No! No! No! Please, ladies, don’t do this!

I get it. A lot of sunscreens out there are thick and greasy. You just want to make it lighter and easier to use (and save yourself some time in the morning too).

But mixing your sunscreen with moisturiser (or anything else, for that matter), dilutes the SPF. Instead than SPF 30, you may well be applying SPF 11!

Is it worth the risk? I don’t think so.

Related: Why You Should NEVER Mix Your Sunscreen With Moisturiser

4. Can You Layer Chemical & Physical Sunscreens?

First things first:

  • Physical sunscreens: Sunscreens that contain only the mineral filters titanium dioxide and/or zinc oxide.
  • Chemical sunscreens: Sunscreens that contain all other UV filters.

That’s the only difference between them. ALL UV filters work by creating a film on the skin that absorbs UV rays and turns them into a less damaging form of energy (heat). Some UV filters also reflect a small amount of UV light away from your skin.

If you want to layer two sunscreens on your face, there’s no reason why you can’t do it. Just be aware that SPF isn’t cumulative.

Here’s why: the SPF number tells you how many UV rays your sunscreen can block.

For example, SPF 30 blocks 97% of UV rays while SPF 50 blocks 98%. So, if you apply a sunscreen with SPF 30 followed by a sunscreen with SPF 50, the layer on your skin will block 98% of UV rays.

In other words, when you layer sunscreens, you get the sun protection of the highest SPF you applied – in this case SPF 50.

Layering isn’t completely useless, though. Most people don’t apply enough and miss spots. If you use two sunscreens, you increase your chances of getting everything covered.

Or, you could just spend a bit more time applying that one sunscreen everywhere. Your choice.

Related: Sunscreen Math: Can You Add Up SPF?

bioderma pigmentbio daily care spf 50+

5. Should You Pat or Rub?

I’m Team Pat all the way.

I know, I know. Sunscreen is thick, it’ll take forever to pat it in. But science shows that’s the right way to do it.

A 2006 study found that “protection by a four star-rated sunscreen (with UVA protection) was optimal when applied as a thin film (40-60% at 2 mg cm(-2)) but less so when rubbed into the skin (37% at 4 mg cm(-2) and no significant protection at 2 mg cm(-2)), possibly due to cream filling crevices, which reduced film thickness.”

Before we go any further, thin film doesn’t mean you can apply less than the recommended amount. It means that, when you apply it properly, sunscreen should form a thin layer on your skin.

If you rub the sunscreen in, you could REMOVE it a little here and there, reducing the thickness of the film (and the sun protection it provides) in some areas.

If you want to rub it in, do it as gently as possible so as not to compromise this thin film.

Related: Pat Or Rub: What’s The Best Way To Apply Skincare Products?

ultrasun extreme SPF 50

6. How Long Do You Need To Wait After Applying Sunscreen Before Going Outside?

20 minutes, give or take.

Let’s be clear: that’s NOT because your sunscreen needs to be activated. ALL sunscreens work straight away.

But you know that sunscreen film I keep talking about? Well, think of sunscreen like paint. It you touch the paint before it’s dry, you’ll remove it.

Sunscreen is the same. Touch your face before it settles and you’ll risk removing the sunscreen in those spots.

It takes 15-20 minutes for sunscreen to form a film on your skin. If you can, wait that long before leaving the house.

Related: The Real Reason You Need To Apply Sunscreen 20 Minutes Before Sun Exposure

7. How Long Should You Wait After Sunscreen Before Applying Makeup?

20 minutes, give or take.

Yes, I’m serious. I just told you sunscreen needs time to settle and form a film on your skin, remember?

You know what happens when you apply foundation straight after sunscreen? You remove it, that’s what.

Let me say it again: anything that touches your face while the film is drying has the potential to remove your sunscreen and compromise its protection.

If you really can’t wait that long before putting on makeup, lightly stipple your foundation on. It’s the gentlest way to apply it.

Related: Is Your Foundation Application Messing With Your Sunscreen?

bioderma photoderm max spf 50 aquafluid review

8. How Often Should You Reapply Sunscreen During The Day?

It depends on how much sun exposure you’re getting during the day.

Let me explain. UV filters get deactivated by sunlight, can be rubbed off of your skin (for example, when you towel dry) or removed through sweat and natural oils.

But how long does it take for this film to become completely ineffective? That’s the million dollar question. You see, the sun’s rays are stronger in some hours (between 10am-4pm) and weaker in others. In winter, the sun is weaker and doesn’t stay around as longer. Sometimes, the sun is completely covered by clouds (but UVA rays will still get through).

Not to mention, you don’t spend the same time outdoors every day. When the weather’s sunny and hot, you can spend hours playing outside. Other days, you’ll just leave the house to get to work and back. On some days, you may not leave the house at all.

In other words, the amount of UV light your skin is getting depends on different factors. And how often you reapply your sunscreen depends on all these factors.

If you’re at the beach, spend a lot of time outdoors, sweat or swim, you need to reapply your sunscreen every couple of hours (it’s easier if you keep your makeup simple).

If you’re getting very little sun exposure, like simply walking to your car and commuting to work, you may not need to reapply at all. Especially in winter.

If you’re getting moderate sun exposure, reapplying once in the middle of the day may be enough. And when you’re in doubt, reapply it (better be on the safe side).

Related: Do You Really Need To Reapply Sunscreen Every 2 Hours?

By the way, if you’re curious to know what my fave sunscreens are, check out these guides below: