A frequent stylist question is what length of shears is best. Sometimes salespeople at trade shows will explain that the correct shear length is determined by placing the shear flat in the palm of your hand, and then by measuring the length from the tip of your longest finger to the heel of the palm of your hand.
Sadly, while this is an exceptionally easy measurement to make, it is almost completely meaningless. On my hand this length is 6.5", and I have relatively small hands. Presumably, this means that I'm only supposed to look for shears that are 6.5"? If I had longer fingers, would this mean I should only look for 8" shears?? Absurd.
Most beauty shears sold today range in length from 5.0" to 7.0", increasing in half-inch increments (5.0", 5.5", 6.0", etc.). Other shears start on the quarter-inch, and move up in half-inch increments (5.25", 5.75", etc.), but this is less common. There are, of course, also longer and shorter shears than this, but these are rare in today's salons.
Broadly speaking, shorter shears are better for detail work and texturizing, and longer shears are better for long straight cuts and deep texturizing.
Of highest importance, is knowing what your salon teaches and expects. Several salons we work with use almost only 6.5" shears, while others allow no longer than 5.5". Knowing this ahead of time simplifies your search significantly.
However, if your salon doesn't set a clear expectation for shear length, versatility is going to be critical. Because of this, your first shear should be toward the middle of the range (maybe between 5.5" and 6.0"). Shears in these lengths are small enough to allow you to do great texturizing and point work, without being so short that you can't get good, clean, straight lines.
By comparison, many salons that cater to men use predominantly 6.5" to 7.0" shears.
Overall, understanding both what your salon expects, and what combination of work you expect to be doing in any given day will help you determine the "ideal" length of shear you should be shopping for. This will provide an excellent starting point for which shears you should be considering in your search.