How to use the tuner
Tap “Enable microphone” and allow microphone access. Play one note at a time, close to the microphone, in a quiet room.
The needle shows the offset in cents (hundredths of a semitone). Centered means in tune; left means flat; right means sharp.
A = 440 Hz or another reference?
The reference A is set to 440 Hz by default, today’s standard pitch. You can change it, for example to 442 Hz to play with an orchestra or a piano tuned slightly higher.