Universal Guitar Tuner image

  Universal Guitar Tuner
      from KEUWLSOFT

Google Play Link


This app is a guitar tuner that uses the microphone to auto detect the pitch of the note being played. The 3 dials will rotate to show the note being played. The middle dial shows the pitch or note name. The inner dial shows the octave. The outer dial will show if the note is flat or sharp - the orange region is within 10 cents and will give good tuning, the green is within 5 cents for even better tuning.

keuwl tuner
Universal Guitar tuner

Tap tuning to enter the tuning select mode to choose from other tuning methods. Tap shift if you need to shift the pitch (for orchestral tuning or to match your out of tune friends). Tap the pitch pipe if you would prefer to tune with a pitch pipe. Any Settings are stored for next time the app is run. To reset to the default configuration (Western 12 TET with no shift), tap reset.

Tuning Select Mode

Tap Tuning to to enter the tuning select mode. The middle dial has the tuning options avaliable, spin to line the required tuning method with the marker. For N-Tone equal temperament, the octave is divided into between 5 and 52 notes as selected by the outer dial. In 5-Limit and Quarter Comma modes there are sub options which are selected by spinning the outer dial. Tap the tuning select button again to return to the normal auto detect mode.

tunings mode
Tuning select mode.

Shift Mode

Shift feature for those that don’t want A to be 440 Hz or if you need to tune to accompany your out of tune friends. Get them to play a note, hit the shift key, and rotate the dial to what they thought they played. Hit the shift key again and then tune as normal. Remember to hit reset to get back to original settings at any time.

shift mode
Tuner in shift mode.

Pitch Pipe Mode

Touch the pitch pipe icon to enter the pitch pipe mode. The currently selected mode will be played. Spin the middle dial to change the note. Spin the inner dial to change the octave. Spin the outer dial to change the volume. Touch the pitch pipe icon again to return to the normal auto detect mode.

pitch pipe mode
Tuner in pitch pipe mode.

Tuning modes in more detail..


12 Tone Equal Temperament (12-TET) is what most western music is written/performed in. It divides each octave into 12 notes with adjacent notes having the same frequency ratio. There are 1200 cents in an octave, and in 12-TET each note is 100 cents apart.

N Tone Equal Temperament

N Tone Equal Temperament allows for custom tuning where you can select N between 5 and 52. The 1200 cents of the octave are then divided up equally by the number of notes per octave selected.

Just Intonation

Just Intonation is formed from ratios of frequencies, such that harmonics will resonate together making a more harmonious sounds when notes are played together. The ratios are:

UnisonC 1:1
Minor secondC# 16:15
Major secondD 9:8
Minor thirdD# 6:5
Major thirdE 5:4
Perfect fourthF 4:3
Augmented fourthF# 7:5
Perfect fifthG 3:2
Minor sixthG# 8:5
Major sixthA 5:3
Minor seventhA# 16:9
Major seventhB 15:8
OctaveC 2:1

Pythagorean Tuning

This is a form of just intonation where the frequency ratios are based on a 3:2 ratio. The ratios are...

C 1:1
D♭ 256:243
D 9:8
E♭ 32:27
E 81:64
F 4:3
G♭ 1024:729
F# 729:512
G 3:2
A♭ 128:81
A 27:16
B♭ 16:9
B 243:128

Quarter Comma Meantone

This app has a standard and extended option for quarter comma meantone tuning. An explanation of quarter Comma meantone and the frequency ratios for the standard mode are found here. Quarter comma can be extended to 24 notes & beyond. The extended 24 note ratios can be found here.


This is a form of just intonation where the frequency ratios are based on powers of 2, 3 or 5, or combination thereof. The ratios for the 4 types of 5-limit tuning used in the tuner are...

NoteSymmetric 1Symmetric 2Asymmetric StandardAsymmetric Extended


Note ratios used in the tuner for 7-Limit tuning are...