How to Tune a Flute. Even the most experienced flautist will sound bad if her flute is out of tune. Unlike many other instruments, you need to consider many variables to play a flute in tune. You must play close attention to the physical tuning of the instrument as well as your natural playing position and embouchure (or lip position).
Determine your tuning base. The most reliable and portable option is an electronic tuner. You can also use a piano or another flute instead. However, being instruments themselves, they're also prone to tuning issues. If you're planning on performing with piano accompaniment and the piano is reasonably in tune, it's best to tune to the piano.
Play a middle B-flat or A note. This is a note you'll play in most concert pieces, regardless of key.
Adjust the head joint in or out, depending on what the tuner says. If you're flat, push the head joint in to make the sound higher. If you're sharp, push the head joint out to make the sound lower.
Fine-tune to your playing style. Play a scale or piece and pay attention to the tuner. If you notice you're tending to be sharp or flat, adjust your playing position on the embouchure plate. If your pitch is flat, you may be rolling your flute in too much and need to roll it out away from your lips. If your pitch is sharp, you're most likely rolling your flute out and need to roll the flute in to cover more of the embouchure plate with your lips.
Alter your style depending on the notes. Even with the perfect position and tuning, some notes may seem off. With the lower notes, the column of air inside the flute is longer than with higher notes. So, you may need to blow slightly harder to achieve the lower notes in tune.
The best way to play in tune more consistently is to practice while paying attention to your tuning. Even if you use the same flute that has been physically tuned the exact same way, you can play sharper or flatter from one day to the next, depending on your playing position, the tenseness of your lips and other factors. Once you practice playing in tune enough, the small adjustments you need to make by rolling in and adjusting your playing technique should become second nature.