According to Precision Piano Service, the average cost to tune a piano that is in otherwise good condition is between $150 and $225, as of 2015. The cost goes up from there, depending on the overall condition of the piano and the amount of time since its last tuning.
For pianos that have not been tuned for a year or two, Precision Piano Service states that it could cost between $225 and $300. Pianos that have not been tuned for two years or longer should first be evaluated to ensure that it can be tuned in the first place. Regular tuning is advised every six months to keep tuning costs down.