US federal debt grew by $63,420 a second in 2025 — and why that is not the deficit

On 30 September 2024 the US Treasury's debt held by the public — the securities owned by investors, banks, foreign governments and the Federal Reserve — stood at $28.3 trillion. A year later, at the end of fiscal 2025, it was $30.3 trillion. The difference, $2.0 trillion, is the figure behind this site's national debt counter: about $63,420 a second, $3.8 million a minute and $5.5 billion a day.

Both balances come from the Treasury's own daily ledger, Debt to the Penny, and anyone can download it. This piece uses that ledger and the Treasury's monthly statement of receipts and outlays to show what the per-second figure is, and what it is not.

Two measures of debt

The headline figure usually quoted is total public debt outstanding, which on 30 September 2025 was $37.6 trillion. It includes $7.4 trillion of intragovernmental holdings — Treasury securities owned by other parts of the government, chiefly trust funds such as Social Security's. That part is money the government owes itself, so economists usually look at debt held by the public instead, which is what the government has borrowed from everyone else.

Total public debt passed $40 trillion for the first time on 18 August 2026, and stood at $40.1 trillion on 28 September. By late September 2026, debt held by the public had already risen by more in fiscal 2026 than in the whole of fiscal 2025, so the pace on the counter is, if anything, now slow.

Why the rise is not the deficit

The federal deficit for fiscal 2025 was $1,775.4 billion: receipts of $5,234.6 billion against outlays of $7,010.0 billion. Put another way, about one dollar in every four the government spent was borrowed. Spread across the year, that deficit comes to about $56,296 a second — noticeably less than the rise in debt.

The gap between the two is normal. Borrowing also has to cover changes in the Treasury's cash balance and the money lent out through federal loan programmes, the largest of them student loans, which are recorded outside the deficit. That is why a counter built on the rise in debt and a counter built on the deficit tick at different speeds, and why the two numbers should not be quoted as if they were one.

Interest now costs more than defence

Net interest on the debt was $970.4 billion in fiscal 2025, up about 10% on the year before, or roughly $30,770 a second. National defence outlays in the same statement were $916.6 billion, about $29,067 a second. Interest has overtaken the entire military budget as a line of federal spending.

Only Social Security, at $1,580.7 billion, was larger among the main functions, with Medicare at $996.7 billion just above interest. Interest differs from all of them in one respect: it buys nothing new. It is the cost of past borrowing, and it rises both when the debt grows and when maturing securities are refinanced at higher rates.

What the counter can and cannot show

The counter spreads one year's increase evenly across every second. Real borrowing is uneven: the Treasury issues securities in auctions on a fixed calendar, tax receipts arrive in large quarterly and April lumps, and the debt limit has in past years forced borrowing to pause and then catch up. Day to day, the ledger can even fall.

It also measures a flow, not a burden. How heavy a debt is depends on the size of the economy that services it and the interest rate it carries, neither of which a per-second rate captures. What it does show honestly is scale: in the time it takes to read this sentence, the government's borrowing from the public grew by several hundred thousand dollars.