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The two most common tunings for a Kalimba are C Major and G Major.

17keys kalimba Target notes:

starting from the middle key/tine:

C => C4

D => D4

E => E4

F => F4

G => G4

A => A4

B => B4

C => C5

D => D5

E => E5

F => F5

G => G5

A => A5

B => B5

C => C6

D => D6

E => E6

use the tuning hammer that comes with the kalimba, optionally a headphone.

Open the app beside the kalimba and press down the middle key "C" in this case. The needle in the app will point to some random hertz(Hz) no. Adjust the key with the hammer very little at a time and try again until the needle in the app points exactly to C4. Similarly keep tuning for the other keys as well. A well tuned Kalimba adjusted properly can hold its tuning for a few weeks (or a bit longer) - depends on usage.