What Is PMI (Purchasing Managers’ Index)?
What is PMI? The Purchasing Managers’ Index is a monthly survey that asks companies whether their orders, output and staff went up or down since last month. Above 50, more of them saw a rise than a fall. Below 50, more saw a fall.
Its advantage is speed. S&P Global’s flash estimate of the September 2026 US manufacturing PMI came out on 23 September, before the month was over (S&P Global). The first official estimate of US GDP for that quarter was not due until 29 October (BEA release schedule).
What the 50 line measures
Each question becomes a diffusion index: the percentage of companies that answered “higher”, plus half the percentage that answered “unchanged” (S&P Global PMI releases).
Say 40% of the panel reports more new orders, 40% the same and 20% fewer. The index is 40 plus half of 40, so 60.
Notice what the sum leaves out: how much orders rose. If every company had 1% more orders than last month, the index would be 100. So a PMI of 55 tells you growth is widespread. It does not tell you output rose 5%.
The headline mixes five answers
S&P Global asks a panel of around 600 US manufacturers, and its headline PMI weighs five of the indices (methodology note):
- new orders, 30%;
- output, 25%;
- employment, 20%;
- suppliers’ delivery times, 15%, turned upside down;
- stocks of purchases, 10%.
The upside-down one catches people out. Slower deliveries push the PMI up, because suppliers are usually slow when they are swamped with orders. But they are also slow when steel is short or a shipping route is blocked, and the index cannot tell those apart.
September 2026 shows both at once. The US manufacturing PMI rose to 55.9 from 53.9, its highest since May 2022. The same release reported lead times lengthening the most since August 2022, with steel and electronics hard to find, and said all five components lifted the headline. Part of that 55.9 was demand. Part was a supply problem counted as strength.
Two US PMIs, two numbers
The US has a second manufacturing PMI, from the Institute for Supply Management (ISM). It builds its headline from a similar set of five questions but weighs them equally. For September 2026 it read 54.5, out at 10:00 a.m. Eastern Time the same morning (ISM release). S&P Global’s came out at 9:45 and read 55.9.
Both said manufacturing grew. They just disagreed by 1.4 points, so when someone quotes “the PMI”, check whose. The one on this site’s calendar is S&P Global’s: its next date is on When is the next S&P Global US Manufacturing PMI? and the forecast and recent results on S&P Global US Manufacturing PMI.
Flash first, final later
For the largest economies, S&P Global publishes a flash PMI about a week before the final, calculated from around 80 to 90% of the responses (S&P Global flash release). The flash is the first look at the month, so it is usually the one the market reacts to.
Usually the final lands close. Since the flash began, the US manufacturing PMI has moved 0.3 points on average between the two. September 2026 was not usual: the flash said 57.0, the final 55.9.
Unlike a jobs report, the survey answers themselves are never revised after publication. Only the seasonal adjustment can change the older figures.
What to read under the headline
- New orders is the most forward-looking part. Today’s orders are next month’s output, so a headline at 51 with new orders below 50 is weaker than it looks.
- Employment is an early hint for the jobs data, such as NFP.
- The price questions show what companies pay and charge, an early read on CPI inflation.
Why PMI moves currencies
Because it comes first, the PMI is one of the earliest clues to what a central bank will do with interest rates. A reading above the forecast points to a stronger economy and rates held higher for longer, which tends to lift the currency. A reading below the forecast tends to weigh on it.
The gap to the forecast matters more than the level. A 52 when 54 was expected is a disappointment, even though 52 means growth.
The other major economies have their own: Euro Area Manufacturing PMI, UK Manufacturing PMI, Japan Manufacturing PMI, Canada Manufacturing PMI and Australia Manufacturing PMI.