Does short or long hair suit you? The 2.25 rule will give you an answer.

There’s a hair hack that's been floating around the interwebs — and we can't stop talking about it. And now you must know about it, too. 

It's called the '2.25 rule'. Heard of it?

We hadn't either. And nah, it has nothing to do with cutting approximately 2.25 inches of hair from your head. 

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The term actually refers to a technique used to determine how long your hair should be, according to the shape of your face. Read: If short hair or long hair suits you better.

And it's gaining MASSIVE popularity because it's so incredibly easy to do.

We love it when that happens!

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Let's just be clear —  this hack has been around for yonks. But, as with everything on TikTok and social media, what's old soon becomes new again. 

So, what exactly does the '2.25 rule' involve?

Allow us to explain.

What is the '2.25 rule'?

Okayokayokay.

According to Google, the term was actually coined by celebrity hairstylist John Frieda, who came up with a clever (and simple) formula to help tell if a short hairstyle will work for your face.

And it involves using two things: a ruler and a pen or pencil.

You basically put the pen under your chin horizontally and hold a ruler in a vertical position under your ear. 

Wherever the pen and ruler meet, is the measurement.

Told you it was simple!

Check it out below: 

@modestpalette My measure was less than 2.25" so short hair it is! #hairrule #shortorlong #haircut #shorthair ♬ money trees - 🍪

So, if the measurement is less than 2.25 inches, you look better with short hair. However, if it's more than 2.25 inches, you look better with long hair.

That's it. Genius.

If you don't have a ruler, you can also use two pens and a measuring tape, as per below:

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A post shared by Laudi Lee - Classic Style tips & Beauty reviews for woman 35+🇿🇦 (@jen_x_style)

The hack obviously all has to do with the angle of your jawbone and what style will accentuate your face shape the best.

We know, we know. Why. Why are we just learning about this now?

Because who else has ever regretted chopping off their hair? (Read: All of us).

The rule is also known as the '5.5cm rule' — depending on which kind of metric you want to use! Either way, it involves exactly the same process.

@velvetrooms Have you tried the 5.5cm rule?? @Glamour wrote about how to measure for the perfect length. What do you think? Have you tried it? #haircut #hairtips #hairconsultation #perfecthairstyle #glamourmagazine #johnfrida #chobham #surrey ♬ Vogue (Edit) - Madonna

Of course, it's important to remember that everyone has their own personal style and there are no hard-and-fast rules when it comes to what you should do with your hair.

So, if you have a hairstyle in mind and want to skip mathematics — you do you.

You gotta admit, though, it's a handy tool if you can't decide wtf to do with your hair.

Have you ever tried the 2.25 rule before? Share your thoughts with us in the comment section below.

Feature image: TikTok;