I'm in my mid-twenties, taking up music for the first time. I started with Guitar, and I'm using online materials to progress. I've been doing this for past 4 months for 1-2 hours per day. Now I'm confused whether I should start learning piano as well in parallel. Would it really help me in learning music theory better? What are the pros and cons in learning both instruments in parallel?
Learning to play the piano can help you learn the fundamentals of music theory, but whether it's better than the guitar, well, it's quite relative. If you want to take music theory far with only the guitar, then you may find it quite challenging in comparison to learning it on the piano.
Piano is of course the go-to instrument for composing music, so when you start learning music theory, everything about theory is laid out for the piano. For instance, when you're learning intervals (measuring the distance between two notes), the piano comes in handy. You can really picture where each piano key is and that each key is designed for every note on the grand staff. In contrast to the guitar, it may take some time for beginners to master intervals. As you see on one guitar string, each fret you move up or down would represent a half step. But moving across strings can become challenging when you're learning theory only on the guitar. In this case, when you want to understand intervals as a whole, it's better to picture intervals on the piano, and you may even translate such knowledge to how guitar strings relate to each other.
As Tim states, learning to play both instruments go hand-in-hand, and it's an excellent decision. I don't see any cons with learning them parallel, though you'll definitely be better at playing one instrument than the other. So it goes back to why you want to learn both at the same time. If you simply have the passion for guitar, but if you feel that learning to play the piano is going help you learn music theory better, then go for it, and continue learning to master the guitar. The pros are that some guitarists learn the basics of both piano and music theory to write music. Others believe that playing the piano strengthens their finger dexterity (this is debatable though!).
If you decide to learn the piano and music theory on it, as well as continue with the guitar, then I take my hat off to you. Feel free to reach out if you have any more questions. All the best for your music endeavours!
That's pretty well what I did as an early teenager. Each helped the other. Figuring out was easier on piano, with its simple layout, whereas on guitar, there are several ways of playing the exact same note. Some songs worked better on one rather than the other, so it was (still is!) good to be able to slide across.
Somehow, playing from dots was better on piano - probably as that's how I was supposed to learn. Most teachers, I expect, do the same still. But on guitar, the actual dots didn't work too well, but that opened up a different avenue - play by ear, which obviously works on piano as well, although I expect, again, that a lot of teachers use the 'play by ear' method far more on guitar.
As both are so different, there's no confusion when playing - you either have your guitar hat or your piano hat on, unlike, say, clarinet and sax. Playing guitar also helps with dexterity of left hand (if that's a correct term!) as the l.h. fingers get a good work out, as opposed to r.h. in early piano. I also found that success was much more instantaneous playing a song with chords on guitar, compared with piano. Only one place to look, for starters.
At that time, also, the propensity to play with others was far greater on guitar - portability, volume, pop status, possibly! So best of both worlds - play by myself - piano, play with others - guitar.
Can't find any downsides, except practice time, which will either double, overall, or get split between the two, to the detriment of one.
Learning theory? Each and both are useful, but more useful still for UNDERSTANDING than learning.