La Liga’s leaders will part with €120m as a guaranteed base fee, with another €40m in performance and appearance-related add-ons that are expected to be triggered.
The 25-year-old has already agreed personal terms with the Catalan club on a five-and-a-half year deal with a €400m release clause.
He will need to undergo a medical before the deal is completed and will move ahead of Ousmane Dembele as Barca’s highest-cost recruit as well as surpass Paul Pogba as the biggest player trade involving an English club.
There is a possibility that Coutinho will attend Barca's hosting of Levante on Sunday, with the club hoping to have him training with his new team-mates on Monday.
Liverpool failed in their exhaustive efforts to convince Coutinho, who did not travel with the squad to a warm-weather camp in Dubai, to remain on Merseyside until the end of the season at the very least.
The Brazilian declined their proposed incentives and offer of a higher wage, repeating his intention to move to Camp Nou with immediate effect.
Having approached the Reds on July 20 with the first of three unsuccessful summer bids bloated by improbable clauses, Barca finally succeeded in their pursuit of the playmaker on Saturday with talks facilitated through his representatives Kia Joorabchian and Giuliano Bertolucci.
Liverpool were definitive in their stance that Coutinho was not for sale at any price in the summer, rejecting his transfer request in the process, but with their No.10 maintaining his desire to depart and Barca finally tabling an acceptable package for his services, Jurgen Klopp agreed to sanction his sale.
The Reds boss told Liverpoolfc.com: “I can tell the Liverpool supporters that we, as a club, have done everything within our means to convince Philippe that remaining part of LFC was as attractive as moving to Spain, but he is 100 per cent certain his future – and that of his family – belongs at Barcelona. It is his dream and I am now convinced there is nothing left at our disposal to change his mind.
“Philippe has made a fantastic contribution to this club over his five years of service and as disappointed as we are he doesn’t want to extend that, the relationship we have for him means with a heavy heart we wish him well.
“The player remained dedicated and committed to helping us win matches, producing good performances and training hard each day at Melwood after the summer window had closed, despite failing to convince us to allow him to leave during that period and that level of professionalism reflects positively on him."
The Brazilian made 201 appearances and scored 54 goals for Liverpool after signing in January 2013 from Inter Milan for just £8.5m.
He will become the third most expensive footballer in the world, behind Paris Saint-Germain pair Neymar and Kylian Mbappe.