Guitar scales are used by guitar players for a variety of reasons. They can be used to learn where the notes are on the neck of the guitar, used for song composition, and used just to strengthen your fingers. No matter how you use scales in your guitar playing, there’s no denying how important scales are to a guitar player. Eve if you don’t consciously apply scales in your playing or you have no idea how scales are instructed, there’s a good chance you’re using them one way or another, so it’s a good idea to put some effort into learning what a scale is and how scales are constructed.
A guitar scale finder can help you do this. What is a guitar scale finder and where can you find one? Take a look online. Several guitar-oriented websites have a built-in feature that allows you to type in a series of notes to find out what scales those notes comprise. There are also a few apps and software programs on the market that will do the same thing.
You really don’t need a guitar scale finder if you take the time to learn some of the basics of constructing scales. A scale is simply a series of notes arranged in a pattern of steps and half steps (a half step equals one fret on the guitar). These patterns are also referred to as scale formulas. By learning the particular step pattern of a scale, you can teach yourself to build a scale in any key simply by applying that pattern to a starting note. The formula for a major scale, for instance, is: Root, W, W, H, W, W, W, H. The “w” indicates a whole step and the “h” indicates a half step. If you start on C and apply these steps, you end up with the major scale in C. If you were to start with a G and follow the same formula, you’d have the major scale in the key of G. This is the formula for a harmonic minor: R, W, H, W, W, H, 1 1/2, H. Learning a few scale formulas, for instance a minor, a pentatonic, or a blues scale, lets you find scales (and even modes) in any key without the use of a guitar scale finder of any kind.
The example below shows the whole and half step markings on the neck of the guitar. When thinking about scales, always remember there is a whole step between all notes except B and C and E and F. There is only a half step between these two sets.
That’s all you really need to know about building scales. Like building chords, once you understand the formulas, you know where to find the right notes.
That’s all you really need to know about building scales. Like building chords, once you understand the formulas, you know where to find the right notes. 
