Looking over the tuning charts while trying to get a new set of strings tuned properly, I am struck by not knowing which octave Middle C on the charts refer to? Is it C3 or C4?

Thanks.

Traditionally middle C is C4. That is what is shown on the tuning charts fourth c on the piano.
With midi it got weird but tradition c4

Thanks, Brett. That's what I thought, but wanted make certain before I started winding.

Unfortunately it can be either depending on the manufacturer of a device. The international standard is that middle C should be C4. However, many companies, like Yamaha, use C3. You really need to know the spec of the tuner you are using.

-Eric

I just tested my electric piano (Yamaha P85) and only by ear I had the impression it was C3. C4 seemed to me an octave too high...just listening to it. Maybe I'm wrong too...

To follow up:

C4 (as reported from the iOS app "APTuner") is middle C. Tuned the Alto using that standard and we are good to go. Had initially tried C3 prior to asking here and it sounded much too low.

Thanks, all!

Is that middle C is located one line under the staff or between the 4th and 5th line inside the staff (treble clef)? Maybe there is a confusion there also.