The Sahm Rule is a recession indicator that triggers when the three-month moving average of the U.S. unemployment rate rises by 0.50 percentage points or more above its lowest point in the previous 12 months. Named after economist Claudia Sahm, who developed it, the rule is designed to detect recessions early, using data that’s already available in real time rather than waiting months or years for official declarations.
How the Calculation Works
The Sahm Rule uses the national unemployment rate (specifically the U-3 measure, the most commonly reported figure). Here’s the step-by-step logic:
- Step 1: Take the unemployment rate for each of the last three months and average them. This is the current three-month moving average.
- Step 2: Look back over the previous 12 months and find the lowest three-month moving average during that period.
- Step 3: Subtract the low point from the current average. If the difference is 0.50 percentage points or greater, the indicator has triggered.
So if the unemployment rate’s three-month average had been as low as 3.5% at some point in the past year but has since climbed to 4.0%, the gap is exactly 0.50 percentage points, and the Sahm Rule would signal a recession is underway. The smoothing effect of three-month averages filters out one-off jumps in a single month’s jobs report, making the signal more reliable than watching any individual data point.
The Federal Reserve Bank of St. Louis publishes the real-time Sahm Rule value on its FRED database, updated monthly after each new jobs report. You can look it up anytime to see where the indicator stands.
Why It Exists
Recessions in the U.S. are officially dated by the National Bureau of Economic Research, but those announcements come well after the fact, sometimes a year or more after a recession has already started. By that point, millions of people may have already lost jobs or income without any coordinated policy response.
Claudia Sahm created the rule while working at the Federal Reserve to solve a specific problem: identifying recessions quickly enough that policymakers could act. Her original proposal tied the indicator to automatic stimulus payments. If the Sahm Rule triggered, direct payments to households would go out immediately, without waiting for Congress to debate and pass legislation. The idea was to build a recession response that works like a circuit breaker, fast and automatic.
Historical Track Record
From 1971 through 2024, the Sahm Rule correctly flagged all seven recessions that occurred during that period. That includes the 1973-75 downturn, the early 1980s double recession, the 1990-91 recession, the 2001 dot-com bust, the 2007-09 Great Recession, and the 2020 COVID-19 recession.
That track record comes with two notable caveats. According to research from the Federal Reserve Bank of Richmond, the indicator produced false positives in 2003 and 2024, reaching or exceeding the 0.50 threshold outside of an actual recession. In both cases, the unemployment rate rose enough to trip the signal, but the broader economy didn’t contract in the way a recession implies.
Why It Can Misfire
The 2024 false positive highlights a structural limitation of the rule. The unemployment rate doesn’t only rise when people lose their jobs. It also rises when more people start looking for work. If someone wasn’t in the labor force (not working and not job-hunting) and then begins searching, they count as unemployed until they find something. In a healthy economy with plenty of openings, that search might still take weeks or months, and during that time, the unemployment rate ticks up.
Sahm herself has acknowledged this dynamic. After the COVID-19 pandemic, millions of workers left the labor force for various reasons: health concerns, caregiving responsibilities, or simply taking a break while savings held up. As those workers returned over subsequent years, and as immigration picked up after pandemic-era lows, the pool of job seekers grew. That pushed the unemployment rate higher even though mass layoffs weren’t happening. “The Sahm Rule right now is overstating the weakness in the economy,” she said in 2024. “But it is picking up on weakness in the economy. It’s telling us something bigger than itself.”
In other words, a triggered Sahm Rule doesn’t always mean a full recession is underway, but it does reliably signal that something meaningful has shifted in the labor market. Hiring may be slowing, job openings may be shrinking, or the balance of power between employers and workers may be tilting. Those are conditions worth paying attention to even if GDP never turns negative.
What It Means for You
The Sahm Rule isn’t a forecasting tool. It doesn’t predict that a recession will happen in six months. It’s a real-time thermometer: when it crosses the threshold, it’s saying the labor market is deteriorating right now, at a pace historically associated with recessions. That distinction matters because it means the indicator is most useful as a confirmation of what’s already happening, not as an early warning of something distant.
For workers and households, a triggered Sahm Rule suggests it may be harder to find a new job, negotiate a raise, or count on steady hours. For investors, it’s one more data point alongside earnings reports, interest rate decisions, and consumer spending trends. It carries weight precisely because it’s simple, transparent, and based on data everyone can see, but it works best when read alongside other indicators rather than treated as a single verdict on the economy.