See below for instructions on how to use this calculator.

[jazzy form=”string_tension”]


  • Original Length is the scale length used to determine tension. You can use any units (inches, mm, cm) but don’t enter the units into the form, only the value.
  • New length should be in the same units as above. This should be the actual scale length of the instrument you want to put the strings on.
  • Old Hz is the original pitch frequency in Hz for the open string note as measured when the tension was determined.
  • Tension can be entered in any units. This is a measure of force and usually is given in pounds (lb) or kg 1. If you  don’t know the original tension, the default value of 100 is used. This then gives a result as percent (%) of the original.
  • New Hz  is the frequency in Hz of the open note you wish to change the tuning to for the string.

You can use the following table to find the appropriate string frequency in Hz for the notes. See my article on Ukulele Strings, Tunings and Technology for a table of tunings and frequencies.

Hz Note Guitar String Ukulele / Tuning
659.2 E
622.2 D#
587.3 D
554.3 C#
523.2 C
493.8 B
466.1 A#
440 A 1st, Std C
415.3 G#
392 G 4th, Std C
370 F#
349.2 F
329.6 E 1st 2nd, Std C
311.1 D#
293.6 D
277.2 C#
261.6 C middle C 3rd, Std C
246.9 B 2nd
233.1 A#
220 A
207.6 G#
196 G 3rd 4th Low G, Std C
185 F#
174.6 F
164.8 E
155.6 D#
146.8 D 4th
138.6 C#
130.8 C
123.5 B
116.5 A#
110 A 5th
103.8 G#
98 G
92.5 F#
87.3 F
82.4 E 6th
77.78 D#
73.42 D
69.3 C#
65.41 C

The following table gives some typical scale lengths of some fretted instruments.

Scale Length (inches) Example
13.6 Standard Soprano Ukulele
14.74 Concert Ukulele
17 Tenor Ukulele
20.1 Baritone Ukulele
23.5 Gibson Byrdland
24 Fender Mustang
24.6 Gretch
24.74 Gibson
25 Paul Reed Smith
25.5 Fender (Stratocaster)
25.6 Classical Guitar (650 mm)


  1. Pounds are an official unit of force. Kg are a unit of mass. I’m a retired scientist and am required to say that. On the earth’s surface at 1 gravity, it’s OK for non-scientist to use either. Scientific units of force are the dyne or Newton.

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