During his first term as President of the United States, Donald Trump made tens of thousands of false or misleading claims.

During the first two-and-a-half years (January 2017–June 2019), the Toronto Star tallied 5,276 false claims, an average of six per day.

Across all four years, fact-checkers at The Washington Post documented 30,573 false or misleading claims, an average of 21 per day.

Fact-checking Trump Trump's statements as president engaged a host of fact-checkers. Tony Burman wrote: "The falsehoods and distortions uttered by Trump and his senior officials have particularly inflamed journalists and have been challenged—resulting in a growing prominence of 'fact-checkers' and investigative reporting." The situation got worse, as described by Pulitzer Prize-winning Ashley Parker: "President Trump seems to be saying more and more things that aren't true."

Glenn Kessler said in 2017 as a fact-checker for The Washington Post there was no comparison between Trump and other politicians. Kessler gave his worst rating to other politicians 20% of the time, but gave it to Trump 64% of the time. Kessler wrote that Trump was the most fact-challenged politician he had ever encountered and lamented that "the pace and volume of the president's misstatements means that we cannot possibly keep up". Kessler and others have described how Trump's lying has created an alternate reality. David Zurawik says we should "just assume Trump's always lying and fact check him backwards" because that's "how to cover a habitual liar".

The Washington Post fact-checker created a new category of falsehoods in 2018, the "Bottomless Pinocchio", for falsehoods repeated at least twenty times (so often "that there can be no question the politician is aware his or her facts are wrong"). Trump was the only politician who met the standard of the category, with 14 statements that immediately qualified. According to The Washington Post, Trump repeated some falsehoods so many times he had effectively engaged in disinformation. Glenn Kessler wrote:

Professor Robert Prentice summarized the views of many fact-checkers:

At the end of 2018, Kessler provided a run-down summary of Trump's accelerating rate of false statements during the year:

Several major fact-checking sites regularly fact-checked Trump, including: PolitiFact, which awarded Trump its "Lie of the Year" in 2015, 2017 and 2019. FactCheck.org, which dubbed Trump the "King of Whoppers" in 2015. The Washington Post said in January 2020 that Trump had made more than 16,241 false or misleading claims as president, an average of about 15 such statements per day. The Toronto Star which said that, as of June 2019, Trump had made 5,276 false statements since his inauguration.

As late as June 2018, the news media were debating whether to use the word "lie" to describe Trump's falsehoods. That month, however, many news organizations, including CNN, Financial Times, Los Angeles Times, Chicago Tribune, The New Yorker, and Foreign Policy began describing some of Trump's false statements as lies. The Toronto Star was one of the first outlets to use the word "lie" to describe Trump's statements, and continues to frequently. Some organizations continue to shy away from the term.

On June 5, 2019, Paul Farhi wrote that Glenn Kessler, author of The Washington Post "Fact Checker" column, had used the word lie only once to describe Trump's statements, although he has sometimes used other terminology that implies lying. Since then, The Washington Posts fact-checking team has written the 2020 book Donald Trump and His Assault on Truth: The President's Falsehoods, Misleading Claims and Flat-Out Lies.

By October 9, 2019, The Washington Posts fact-checking team documented that Trump had "made 13,435 false or misleading claims over 993 days". On October 18, 2019, the Washington Post Fact Checker newsletter described the situation:

After departing the White House, January 20, 2021, Trump gave a farewell address at Joint Base Andrews in Maryland prior to departing on Air Force One for his residence in Palm Beach, Florida. The AP fact-checked his speech, and reported that it included false statements about his presidency and administration's accomplishments. These included statements that he passed the largest tax cuts in history; that the U.S. economy during his tenure was the greatest in U.S. history; that he achieved record job creation; that his administration rebuilt both the U.S. military and the American manufacturing industry; that he destroyed the ISIS caliphate; and a reiteration of his previously repeated falsehood that he, and not former President Barack Obama, had passed the Veterans Choice Act. These falsehoods added to the 30,573 falsehoods that The Washington Posts fact-checker had tallied by the end of Trump's presidency, an average of 21 falsehoods a day.

Scholarly analysis of Trump's tweets found "significant evidence" of an intent to deceive:

Credibility polling According to a September 2018 CNN-SSRS poll of 1,003 respondents, only 32% percent found Trump honest and trustworthy, the worst read in CNN polling history. The number was 33% on election day, November 8, 2016. In June 2020, a Gallup poll of 1,034 adults within the U.S. found that 36% found Trump honest and trustworthy. By comparison, 60% of respondents found President Obama honest and trustworthy in June 2012 during his re-election campaign.

Re-election campaign During the Trump's re-election campaign, he defended his actions and criticized the media. At a rally in February 2017, he referred to a nonexistent incident ("last night in Sweden...") while criticizing the asylum policies of several European countries. After backlash from the press and the Swedish government, Trump said he was referring to a Fox News program aired the previous day.

Commentary and analysis As president, Trump frequently made false statements in public speeches and remarks. Trump uttered "at least one false or misleading claim per day on 91 of his first 99 days" in office according to The New York Times, and 1,318 total in his first 263 days in office according to the "Fact Checker" political analysis column of The Washington Post. By the Posts tally, it took Trump 601 days to reach 5,000 false or misleading statements and another 226 days to reach the 10,000 mark. For the seven weeks leading up to the midterm elections, it rose to an average of 30 per day from 4.9 during his first 100 days in office. The Post found that Trump averaged 15 false statements per day during 2018.

The New York Times editorial board frequently lambasted Trump's dishonesty. In September 2018, the board called him "a president with no clear relation to the truth". The following month, the board published an opinion piece titled, "Donald Trump Is Lyin' Up a Storm".

James Comey had frequent discussions with Trump, and in his first major interview after his firing he described Trump as a serial liar who tells "baffling, unnecessary" falsehoods:

The Washington Post commentator Greg Sargent pointed out eight instances where government officials either repeated falsehoods or came up with misleading information to support falsehoods asserted by Trump, including various false claims about terrorists crossing or attempting to cross the Mexican border, that a 10% middle class tax cut had been passed, and a doctored video justifying Jim Acosta's removal from the White House press room.

James P. Pfiffner, writing for The Evolving American Presidency book series, wrote that compared to previous presidents, Trump tells "vastly" more "conventional lies" that politicians usually tell to avoid criticism or improve their image. However, Pfiffner emphasized that "the most significant" lies told by Trump are instead "egregious false statements that are demonstrably contrary to well-known facts", because by causing disagreements about what the facts are, then people cannot properly evaluate their government: "Political power rather than rational discourse then becomes the arbiter."

Selman Özdan, writing in the journal Postdigital Science and Education, describes that "many" of Trump's statements in interviews or on Twitter "may now be classed as bullshit", with their utter disregard for the truth, and their focus on telling "a version of reality that suits Trump's aims". She added that these statements are "often" written in a way which criticizes or mocks others, while offering a misleading version of Trump's accomplishments to improve his image.

Daniel Dale, writing for The Washington Post, described fact-checking Trump as being "like fact-checking one of those talking dolls programmed to say the same phrases for eternity, except if none of those phrases were true", noting that Trump had repeatedly and falsely claimed that he had passed the Veterans Choice Act and that U.S. Steel was building six, seven, eight or nine plants (the company had invested in two existing plants). Dale added: "Many of Trump's false claims are so transparently wrong that I can fact-check them with a Google search." In 2019, Dale noted that Trump had a tendency to use large inaccurate numbers instead of smaller accurate ones.

Susan Glasser wrote that falsehoods are "part of his political identity" and quoted Glenn Kessler's description of them as "Trump's political 'secret sauce'". She described how "The White House assault on the truth is not an accident—it is intentional." When comparing Trump to Richard Nixon, she quoted Barry Goldwater, who described Nixon as "the most dishonest individual I ever met in my life", but she did not stop there. She spoke to Morton Halperin "who oversaw the writing of the Pentagon Papers and then served on Nixon's National Security Council staff... Halperin insisted, strongly, that Nixon wasn't nearly as damaging to the institution of the Presidency as Trump has been. 'He's far worse than Nixon,' Halperin told me, 'certainly as a threat to the country'."

Purpose and effect

A few days after Trump's January 20, 2017, inauguration, some experts expressed serious concerns about how Trump and his staff showed "arrogance" and "lack of respect...for the American people" by making "easily contradicted" false statements that rose to a "new level" above the "general stereotype that politicians lie". They considered the "degree of fabrication" as "simply breathtaking", egregious, and creating an "extraordinarily dangerous situation" for the country.

They elaborated on why they thought Trump and his team were so deceptive: he was using classic gaslighting in a "systematic, sophisticated attempt" as a "political weapon"; he was undermining trust and creating doubt and hatred of the media and all it reports; owning his supporters and implanting "his own version of reality" in their minds; creating confusion so people are vulnerable, don't know what to do, and thus "gain more power over them"; inflating a "sense of his own popularity"; and making people "give up trying to discern the truth".

Specific topics

Inaugural crowd Trump's presidency began with falsehoods originating from Trump. On the day after his inauguration, he falsely accused the media of lying about the size of the crowd. He then exaggerated the size, and White House press secretary Sean Spicer backed up his claims. When Spicer was accused of intentionally misstating the figures, Kellyanne Conway, in an interview with NBC's Chuck Todd, defended Spicer by saying he merely presented alternative facts. Todd responded by saying, "Alternative facts are not facts; they're falsehoods."

In September 2018, a government photographer admitted he, at Trump's request, edited pictures of the inauguration to make the crowd appear larger: "The photographer cropped out empty space 'where the crowd ended' for a new set of pictures requested by Trump on the first morning of his presidency, after he was angered by images showing his audience was smaller than Barack Obama's in 2009."