Trump finalized reciprocal tariff rates moments before announcement using back-of-envelope math — and Googled his own numbers

Donald Trump had not settled on the details of his reciprocal tariffs until moments before their announcement on April 2 last year, ultimately working out the rates through rough back-of-envelope calculations with Peter Navarro, his White House adviser on trade and manufacturing. Trump also distrusted official data submitted by the Office of the United States Trade Representative, directing aides to search Google for numbers more to his liking — and when the announcement drew fierce criticism, he turned around and blamed Navarro, according to a new book.

Maggie Haberman and Jonathan Swan, White House correspondents for The New York Times, published a new book Tuesday titled "Regime Change," offering an account of the internal White House dynamics surrounding "Liberation Day," the administration's name for the reciprocal tariff announcement.

According to the book, Commerce Secretary Howard Lutnick and Treasury Secretary Scott Bessent were tasked, in the days before the announcement, with contacting trading partners around the world to deliver a warning. But because neither secretary knew the specifics of the tariff policy, they could do little more than urge trading partners not to retaliate — because at that point, Trump himself had not yet decided what the tariffs would be.

The authors write that the rates remained undecided until the last moment because the policy was not the product of rigorous analysis or simulation, but was instead being shaped by Trump's personal instincts and stubbornness.

Trump so distrusted his administration's own official documents that he ordered aides to "Google" figures that matched his expectations. When the USTR submitted data on the tariff rates trading partners charged the United States — routed through Lutnick — Trump dismissed it. "These are f---ing bulls--- numbers," he said, according to the book. Trump insisted that the rates China and India charged the United States were far higher than what the USTR had compiled. The authors recount that Lutnick turned to USTR chief Jamieson Greer and pressed him to say something, but Greer stayed silent, unwilling to confront Trump.

Trump sought to replace the government's data with figures he found through Google searches. On March 26 last year — a week before Liberation Day — Trump held a tariff strategy meeting with aides in the Oval Office and complained, "Nobody's bringing me the f---ing numbers." He then turned to Natalie Harp, an aide sitting against a wall in the corner of the room, and told her: "Google it. And bring me the real numbers."

Harp stays close to Trump, searching social media and news for him and handing him printouts. Trump's trust in her ran so deep that he was known to say, "She never leaves me."

Trump ultimately settled on the reciprocal tariff rates by working through the math with Navarro. The rates were calculated by dividing the trade deficit with each country by the value of imports from that country, then halving the result. There was no particular theoretical basis for the formula.

Reports that White House staff were themselves bewildered by the arbitrarily derived rates had emerged through multiple channels even before the book's publication. Lutnick, venting his frustration over the methodology to close associates, made a self-deprecating joke: "I only went to middle school" — an apparent dig at Navarro, who holds a doctorate in economics from Harvard University.

Trump had worked out the tariff rates side by side with Navarro, yet when fierce criticism began the day after the announcement, he turned on his adviser, calling them "Peter's f---ing stupid numbers." The reciprocal tariffs immediately began to damage the US economy: the S&P 500 plunged 12 percent over two days on the New York Stock Exchange. Even US government bonds, long considered a safe asset, were sold off heavily, sending yields surging as prices fell sharply.

Even so, the authors write, Trump pushed to hold the irrationally high tariff rates in place longer than aides including Bessent and Lutnick could bear. Bessent privately marveled at Trump's high tolerance for risk, citing it as a key factor in his political success. Bessent compared Trump to his former boss, hedge fund legend George Soros, saying the two were "the same kind of animal" — both possessed of a strong appetite for risk and a remarkable capacity to survive it.