Luthier's Toolkit - FRETS
The Luthier's Toolkit - Frets is a simple application for calculating the fret slots on an an acoustic instrument for a given scale length. - A brief explanation of scale length
Main Screen

The main screen contains two editable field: Frets and Scale.

These two values may be changed by tapping on the displayed value.

The constant used for calculating the scale length is displayed above the edit fields.

Below ( or in landscape to the right ) the calculated fret positons are displayed. The first number is the distance the fret slot appears from the Nut. The second column displays the actual width of the fret.
Main Screen - Changing the Scale

The screen shot to the left show the Scale Length being edited. The keyboard was activated by tapping on the white edit area ( here showing the value 640 ).
Constant Screen - Changing the Constant

For most instruments the default constant ( 17.817 ) is correct. If there is a need to change the constant the "Change Constant" option on the menu ( upper right of the main screen ) may be used to set the constant to any value.

The "Reset" button may be pressed to restore the constant to its default value.
Constant Screen - Emailing the Fret Slot Calculations

The "Send Email" option ( menu upper right of the main screen ) may be used to send the currently displayed calculations to an email address.

Type in a valid email address and hit send. This will open the phone's email program with an email message ready to go. The body of the email will contain the calculations currently displayed in the application.

An example of the fret slots displayed in an email ready to be sent.