The crop is the hottest thing in hair right now as Rosie Huntington-Whitley, Lily Collins and Scarlett Johansson all go for the chop.

More celebrities than ever are lopping off their long locks every day, and so the normal woman's temptation for a dramatic change is inevitable.But before march to the salon with a picture of Mary Quant, note the latest theory for when to chop and when to stop - the foolproof 2.25-inch rule.

If you're thinking about the right hair length for your face, you don't need to consult with a stylist, do a lot of research, or pull back your hair, squint your eyes and try to imagine your face with a short hair style. All you need is a ruler and a pencil, and The 2.25-inch (5.5cm) Rule.

International Training Director of Color Wow and Senior Stylist at John Frieda Salons UK, Giles Robinson, says: It's all about the angles. The Rule was created by John Frieda, and it is a fool-proof guide for hair stylists to use so they can tailor the cut to make the length asflattering as possible to the face shape.


Grab a ruler and a pencil. Place the pencil under your chin horizontally. Then place the ruler under your ear,vertically.Theintersection of the pencil and ruler indicates a measurement. If it is less than 2.25 inches, then like Halle Berry and Audrey Hepburn, your face is made for short hair. If that measurement is more than that length, like Kim Kardashian and Sarah Jessica Parker, then long hair will be the most flattering choice.

So, the next time you're admiring someone's short crop, or longing after their long hair, just remember The 2.25' Rule... if the distance from the bottom of your ear to your chin is greater than 2.25', you might want to stick with longer haircuts. If that distance is less than 2.25', you have a face suited to short hair, even a super-short pixie cut.