The Mandela family trust will receive $130,000, plus royalties. Others to benefit include the governing ANC, personal staff and several schools.
Mr Mandela's third wife, Graca Machel, was likely to waive her claims to the estate, the executors said, although she is entitled to half of it.
Mr Mandela died in December, aged 95.
The former president left behind an estate that includes an upmarket house in Johannesburg, a modest dwelling in his rural Eastern Cape home province and royalties from book sales, including his autobiography Long Walk to Freedom.
Speaking at the Nelson Mandela Foundation in Johannesburg, Mr Moseneke said the 46m rand was based on "rough and ready estimates" and the final amount could be very different.
"We are yet to get down to the business of finding the asset, listing them and valuing them and accurately reflecting them. We have a duty to file a provisional inventory."
The final amount "could be one 10th of what we've said the value is, it could even be double", he said.
Justice Moseneke, who is also deputy head of South Africa's Constitutional Court, said some of the estate would be split between three trusts set up by Mr Mandela, including a family trust designed to provide for his more than 30 children, grandchildren and great-grandchildren.
The family trust will receive 1.5m rand, plus royalties.
Schools the former president attended are due to receive 100,000 rand each, as are Wits and Fort Hare Universities, for bursaries and scholarships.
The ANC (African National Congress) will also receive some royalties, to be used at the discretion of the party's executive committee, to spread information about the party's principles and policies, particularly concerning reconciliation.
Mr Mandela's children each received loans worth $300,000 during his lifetime and will have that debt scrapped if it has not been repaid.
Close personal staff, including long-time personal aide Zelda la Grange, each get 50,000 rand.
The home in Houghton, Johannesburg where Mr Mandela died on 5 December will be used by the family of his deceased son Makgatho.
"It is my wish that it should also serve as a place of gathering of the Mandela family in order to maintain its unity long after my death," the former statesman wrote.
The mood of the Mandela family when the will was read was "charged with emotions but it went well," said the executor, who added that the Mandela family were "well pleased" by his will.
Despite this, there are fears the will could set off another round of squabbling among members of his large and factious family.
Mr Moseneke said there was a 90-day period in which the will can be contested.
The will was first written in 2004 and last amended in 2008.