certum est quod certum reddi potest

it is certain, whatever can be rendered certain

Notes

Or "... if it can be rendered certain." Often used in law when something is not known, but can be ascertained (e.g. the purchase price on a sale which is to be determined by a third-party valuer)

Words

quod – because, that, the fact that, the point that, what, whereas, which
certo – dispute, fight, settle, to contend, to settle by combat, to struggle
reddo – answer, deliver, hand over, imitate, pay up, recite, render, represent, restore, return, surrender, to give back, to impart, to repeat, translate