How Much SPF Do You Need To Put On Your Face?

15/05/2017 11:57 BST | Updated 15/05/2017 11:57 BST

Summer is so close you can almost taste, touch and feel it. While applying SPF to your face should be an all-year-round affair, it's understandable why the anticipation of evening BBQs, park picnics and lazy Sunday lounging has you wondering...

'Just how much SPF should I really be putting on my face?'

'How often do I need to reapply my SPF?'

'How do I know this bottle of sunscreen is going to effectively defend my skin against sunburn, age spots, fine lines and wrinkles?'

...because this is the real reason you use sunscreen right?

Not to avoid tanning, but rather to prevent the dreaded jowls chasing you prematurely.


Hernán Piñera via flickr

The average amount of sunscreen us 'brits' apply is only 20-50% of the recommended dose.

Most people do not apply enough sunscreen to provide their skin with the protection rating stated on the bottle - are you one of them?

Why does sunscreen application matter?

Sunscreen does what it says on the tin, only when careful directions are followed. When used 'as directed' sunscreen protects your skin against the damaging effects of UV light to the standards described on your carefully selected bottle.

It's able to do this thanks to a magic number.


This is the thickness of sunscreen that needs to be applied to every centimetre of your skin, for any validated sunscreen to work effectively.

Every accredited sunscreen legally sold on market has to visit a testing lab before it's officially signed-off. During this visit new sunscreen formulas are scrutinised for their UV protection. To ensure all testing is fair, every sunscreen trialled is placed under the exact same conditions.

Can you take a guess at one of those conditions?


Testing squares are spread with 2mg/cm2 of sun cream, UV light is shone at them and results are collected.

How much sunscreen do you need to put on your face?

2 milligrams per centimetre squared doesn't mean much. What does our magic number equate to in real-life terms?

Is it a thimble full? A shot glass? A 2-pence piece?

First, we need to know the average size of a face i.e. how many cm2 areas are there on an average human face?

Then, we need to multiply this number by 2mg.

Finally, we need to work out an easy, 'go-to' measure for that number.

Helpfully scientists Nicki Zevola Benvenuti and co. have done the hard work for us and the answer is simple.

1-quarter teaspoon.

2mg/cm2 is the equivalent of 1-quarter teaspoon for an average sized human face.

Are you applying enough?

Borrow a quarter teaspoon measure from your kitchen, fill it with your chosen sunscreen and apply. Does it feel and look like the amount you'd normally use?

If your answer is yes - great, your skin is safely protected.

If your answer is no - move that quarter teaspoon to your vanity top and use it to measure your sunscreen application for a week.

Do you have more questions? Find the answers to 9 more of your most commonly asked sunscreen questions, here.