The Top Five Debt Contributors by PercentageFranklin D. Roosevelt (1933-1945): President Roosevelt had the largest percentage increase to the debt. Although he only added $236 billion, this was a nearly 1,050% increase from the $22.5 billion debt level left by President Herbert Hoover. The Great Depression and the New Deal contributed to FDR's yearly deficits, but the biggest cost was World War II: It added $186.3 billion to the debt between 1942 and 1945.
Woodrow Wilson (1913-1921): President Wilson was the second-largest contributor to the debt, percentage-wise. He added $21 billion, which was a 724% increase over the $2.9 billion debt of his predecessor. World War I contributed to the deficits that raised the national debt.
Ronald Reagan (1981-1989): President Reagan increased the debt by $1.85 trillion, or by 186%. Reagan's brand of supply-side economics didn't grow the economy enough to offset the lost revenue from its tax cuts. Reagan also increased the defense budget by 35%.
George W. Bush (2001-2009): President Bush added $6.1 trillion, or a 101% increase, putting him in fourth. Bush launched the War on Terror in response to the 9/11 attacks, which led to multi-trillion-dollar spending on the War in Afghanistan and the Iraq War. Bush also dealt with the 2001 recession and the 2008 financial crisis.
Barack Obama (2009-2017): Under President Obama, the national debt grew the most dollar-wise ($8.6 trillion) but was fifth in terms of percentage: 74%. Obama fought the Great Recession with an $831 billion economic stimulus package and added $858 billion through tax cuts.
6th: George H.W. Bush - 54% increase in national debt / $1.55 trillion added to national debt
7th: Gerald Ford - 47% increase in national debt / $220 billion added to national debt
8th: Jimmy Carter - 43% increase in national debt / $300 billion added to national debt
9th: Richard Nixon - 34% increase in national debt / $120 billion added to national debt
10th: Donald Trump - *33% increase in national debt / $6.7 trillion added to national debt (Figures as quoted in linked article from thebalance.com.)
*
Actual debt calculations, including most recent 2020 data, are 39% increase in national debt / $7.8 trillion added to national debt.
https://www.thebalance.com/us-debt-by-president-by-dollar-and-percent