We often get asked by our piano students and teachers questions about piano tuning. Is there a mistake in my sheet music, or is my piano just out of tune?
In general, you should tune your piano every year if you live in a dry region and every 6 months if you live in a humid region.
Piano tuning tends to cost around $173 on average, according to CostExaminer. This will of course depend on your location - major cities tend to cost more, and if your piuano needs a pitch raise. Students often say that after a piano tuner does a pitch raise, it makes a huge difference in quality of sound.
Try hitting every key and see if there is a wavering note or a note that sounds flat or sharp when it shouldn't be. You can also play a scale like c major and play a recording from youtube to compare.