Stitch ratio for sleeve to front/back for raglan

Is there a formula to figure out how many sleeve stitches to front/back stitches to cast on when making a top down raglan sweater. I have tried three times to get the ratio of sleeve to front/back stitches correct to make a bolero style crop jacket. I am trying to tighten up the back neck yoke while keeping the correct depth and width in the shoulder area. I would prefer to fix this at the cast on row rather than go back and pick up stitches and knit up to tighten the neck.

This might help. It’s a formula for a custom fit raglan pattern.

Usually about 1/3 of the sts for the back, 1/3 for the front and 1/6 each for the sleeves. If the fronts start out with just 1 or 2 sts each though and increase as in a V neck, deduct those sts from the total number and half the remaining ones would be on the back 1/4 each for the sleeves. In other words, the back and both sleeves would be equal in number.