To calculate the placement of your buttonholes for the right front placket, start by determining the total space available for the buttons and buttonholes. With 86 stitches on your left band, you’ll use a similar stitch count for the right band. Since you have 5 buttons, you will need 5 buttonholes, plus you need to leave space for the buttonholes themselves. Assume each button takes up about 1 inch (or roughly 2 stitches, depending on your gauge) and you’ll want to place your buttonholes evenly. Measure the total length of your placket in inches, then subtract the total width of the buttons (5 inches for 5 buttons).
This will give you the remaining space for the buttonholes, which should be divided evenly by the number of gaps (6) created by the buttons (one before the first button, one between each pair of buttons, and one after the last button). Adjust for the number of stitches that will fit into this remaining length to calculate the exact number of stitches between each buttonhole. Make sure to leave an equal number of stitches at the beginning and end for a balanced look, typically 1-2 stitches on each end, depending on your design preference.