The much-anticipated move will influence mortgages, credit card, and saving rates for millions of people in the US and even around the world.

We won't know exactly how big a cut the Federal Reserve will make, or how much lower rates might fall, until the announcement.

The Federal Reserve's key lending rate, which it charges banks to borrow, sets a base for what companies charge people in the US for loans, like mortgages, or other debt, like unpaid credit card balances.

That rate has hovered around 5.

3% for more than a year, the highest level since 2001, since jumping from near zero at the start of 2022.

A cut will bring some welcome relief to borrowers, though it will likely mean that some banks knock down the rates they are offering savers too.

Americans will be most directly affected by a change.

But central banks with currencies tied to the dollar often link their rate decisions to the Fed, such as Hong Kong and many Gulf states, so borrowers in those countries will also see an impact.

For the many people outside of the US invested in the US stock market, a cut is also likely good news.

First, it means companies can borrow debt for less money and reinvest it to make the business more profitable.

Second, lower rates mean savings accounts and some other kinds of investments become less attractive, so investors tend to move their money towards things like stocks.

Europe, the UK, New Zealand, and Canada have cut rates already, and so have many banks in emerging markets.

Those banks all had their own reasons for cutting rates, and how low the Fed decides to go depends a bit on what's pushing it to act.

In 2022, when the Fed started raising interest rates, officials were focused on inflation and wanted to get consumer prices, then rising at the fastest pace since the 1980s, to stabilize.

A jump in rates tends to bring down prices by making it harder to borrow, so people spend less on everything from consumer goods to homes and business equipment.

But less demand also means the economy isn't growing as quickly, and if it slows too much and actually starts contracting then that’s a recession.

In the past, the US economy has often entered recession after a series of rate hikes, costing millions of people their jobs.

So is the Fed cutting rates because it has triumphed in its fight against inflation or because the economy is in peril? Officials have said they're increasingly confident inflation is headed back to normal, so their attention is turning to the risks to the job market.

Republicans and Democrats have been watching this Fed's moves closely for two years, and a cut will likely help Democrats as the party in power.

But Fed chair Jerome Powell has said time and again that the bank is focused on economic data, not politics, in making its move.

Analysts are divided about whether the Fed will announce a cut of 0.

25 percentage points or go for a bigger, and more unusual, 0.

5 percentage points cut.

For a bank that has tried hard to telegraph its moves well in advance, the level of uncertainty is unusually high.

An isolated rate cut, even a bigger one, might not make that much of a difference to regular borrowers.

But this meeting is expected to mark the start of a series of actions that will bring borrowing costs lower over the next year or so.

Mr.

Powell will presumably be asked about it at the press conference after the bank's announcement, and he will presumably say it will depend on the data—his go-to response.

But the Fed will release a chart showing what its members predict, which could help shape that picture.