Eubank will have to weigh in one final time at about 08:00 BST on Saturday in line with the rehydration clause.
Neither Benn nor Eubank are allowed to put on more then 10lbs from the 11st 6lb limit.
Benn, 28, weighed 11st 2lb and is not expected to have any issues with the rehydration limit.
For Eubank, he says he is still unsure how he will approach the next 24 hours. He will be fined again if he misses weight.
“This is the peculiar situation that I find myself in,” said Eubank.
“I have to watch what I eat and drink, or I can eat and drink whatever I want but then I have to get in the sauna tomorrow morning and sweat off 4lb – I still don’t know which one I’m going to do.”
Benn is coming up two weight classes to fight Eubank and the fine will go directly to the unbeaten welterweight.
The pair will fight three decades after their fathers’ rivalry in the 1990s and two and a half years since Benn’s failed drug tests led to the cancellation of their 2022 bout.
Benn has always denied intentionally doping and had his suspension lifted in November 2024.
Despite Friday’s hefty fine and mental drain for Eubank, he said the only victory to celebrate will be when his “arm is raised”.
“If they want to look at this as their victory then that’s great for them,” he added.
“All that matters for me is who performs on the night, who puts in on the line and who represents their family name to the best of their ability.”
