Executive vice-chairman Ed Woodward is studying the sums following the Italian giants' £88million bid to lure the Portugal superstar from Real Madrid.
United are not frightened by the fee or his salary, which is more than £500,000 a week.
They are prepared to offer their former star, 33, who quit for the Bernabeu in 2009, a three-year-deal. And they are also not worried by Ronaldo's poor relationship with Jose Mourinho during their time together at Real.
United are well aware no deal has been struck with Juve, who would also be financially stretched to pay the sums mentioned.