Splitting Slurry?

I’ve been building up a slurry of WLP830 for a few weeks for a 10 gal batch of O’fest.  Is there a good way to split the slurry into 2 fermenters out of a 5000ml flask, other than eyeballing it?
-J.K.L.

I cold crash the starter, decant the spent wort leaving a tad to swirl up the yeast, vigorously swirl it up to homogenize, and pour into a sanitized measuring cup. Pitch immediately. Makes it easy to pitch half and half.

I do the same, swirl and pour into a measuring cup, a cup at a time, alternating carboys until it’s gone.