I recently found out about the claims of this guy being the wealthiest man ever. I find it a dubious claim at best. I don't doubt he was a fabulously wealthy man compared to the rest of the contemporary population, but richest EVER seems a stretch.
Mostly because this fact only seemed to surface about 5 years ago, and the only source I can find is www.celebritynetworth.com. Of course there are many many sites and articles since referencing this site indirectly as "historians". This site seems the kind to throw up any kind of rubbish if it results in more clicks.
So what are the reliable estimates of Musa's actual wealth? How many tons of gold? How many tons of salt? How much wealth was there in north Africa at that time, compared to Europe and the East?
As with all historical wealth, it is hard to evaluate changes in inflation and wealth over long periods of time. One of Mansa Musa's claims to fame is his pilgrimage to Mecca. Supposing that him bringing along 12,000 slaves each carrying 4 pounds of gold is correct on the number of slaves and weight of gold per slave, 48,000 pounds of gold is approximately $800 million of gold at modern market prices. Clearly he was very rich but it's hard to estimate how rich.
He also supposedly outfitted the 48,000 non-slave members of his pilgrimage, but how much would this cost in today's dollars? We can estimate a set of common clothes today would cost $100-200, or we could total up the number of hours a set of clothes took to make in 1320 and convert that to the wage a tailor makes today to get a significantly different sum.
Lastly, suppose we consider him owning the 12,000 slaves he brought on the pilgrimage. Slave prices in the US were roughly $100 in the early 1800s ($2200 in 2016 dollars) and $500 by 1860 ($15,000 today). The former adds up to $26 million of slaves while the latter $180 million.
So depending on how you account for inflation and the value of Mansa Musa's holdings 700 years ago, I'm sure you could arrive at him being the wealthiest man ever but it seems that such a conclusion would be misleading at best.
Let's make a generous assumption that everything detailed here about Musa is true. If so, then who would have been Mansa Musa's next closest rival in terms of personal wealth during this time?