Deciding whether to take the plunge and chop the hair you've spent ages growing can be an agonizing decision. Will it suit you? What if it doesn't? How long will it take to grow back?Well, here's a nifty little trick that should help you decide whether or not to go for the big chop or not. Giles Robinson, director of a hair colour company and stylist for John Frieda salons, developed this technique to determine whether a short haircut would suit a person. He stated that 'it's all about the angles.'The rule is called the '2.25 inches\/5.5 centimetre rule' and it's very simple to try at home. SuppliesPencilRulerInstructions Place the pencil horizontally underneath your chinPlace the ruler directly underneath your earlobe (vertically)Take a look at where the pencil and ruler meet because that will tell you whether or not you should cut your hairIf it is less than 5.5 centimetres then you would look great with short hair. However, if it's more than that then stick with long hair because it's better suited for your face shape. Check out the video above to see exactly how to put this technique into practice!