U.S. Open 2025: This device will be all the rage at Oakmont. So what is a Stimpmeter anyway?

For the first time since 2016, and the 10th time in U.S. Open history, the USGA is bringing its marquee championship to Oakmont Country Club outside Pittsburgh. The famed course has proven to be a difficult test over the years, Dustin Johnson’s four-under 276 total in 2016 proving the best winning score.

Between media day social hits, Rory McIlroy and Adam Scott’s brutal practice round and Bryson DeChambeau’s latest YouTube video, all indications point toward another daunting task ahead. The fairways are extremely narrow and the rough looks ridiculously long. And then there’s the speed of Oakmont’s greens.

“The fast greens are in the DNA of Oakmont,” said Darin Bevard, the USGA Senior Director of Championship Agronomy.

Indeed, the club prides itself on the slick putting surfaces. So much so that a USGA source said that the greens are being slowed down from an outing held at the club last Monday.

Given Oakmont’s uncanny greens, you’ll inevitably hear throughout U.S. Open week about the Stimpmeter, a tool used to measure a green’s speed by seeing how far a golf ball rolls off a ramp. The amazingly simple device was created in 1935 by Edward S. Stimpson, the idea originating after Stimpson observed Gene Sarazen putt a ball off a green into a bunker during that year’s U.S. Open at … wait for it … Oakmont.

A Stimpmeter’s measurement is referred to in “Stimps,” which is the average distance a golf ball rolls off the Stimpmeter in feet. Most everyday golfers encounter greens with a Stimp reading in the eight-to-10 range, while the typical PGA Tour event is around 12.

The higher the Stimp, the faster the green. At this year’s U.S. Open, Bevard says Oakmont’s Stimp will be in the range of 14½-15 feet at the beginning of rounds—a lightning fast speed.

Stimpson, who was a former captain on Harvard’s golf team, missed a short putt in the 1926 New England Amateur that cost him a title. World Golf Hall of Fame Director Michael Trostel says the missed putt spurred a lifelong interest for Stimpson in putting strategy.

“I think for Stimpson, observing the best players in the world struggling on these greens in 1935, it really got him wondering how fast the greens in Oakmont were during the championship,” Trostel said.

Later that year, the first Stimpmeter—which was made of wood, 30 inches long and had a notch where a golf ball would sit—was born. As one end of the Stimpmeter was slowly raised, a ball would then roll down the track at a uniform speed, with the notch where a ball rested before rolling down ensuring a consistent release point, which makes it so effective in measuring speed.

To calculate Stimp, three balls are first rolled off the Stimpmeter on a flat surface. The average distance of each of the three rolls is taken before the process is repeated by rolling the balls in the opposite direction. That average is determined, and the average of the two averages comes out to the Stimp.

"Speed of a green really means, if I always putt the ball with exactly the same putting stroke, the speed of the green tells me how far it's going to roll out,” said Steven Quintavalla, USGA’s Senior Director for Equipment Research and Testing. “So for a fast green, it's going to roll out farther than a slow green again, given that exact same putting stroke."

Interestingly, it wasn't until 1976 that the Stimpmeter made its USGA national championship debut at the Atlanta Athletic Club. Before the USGA rolled out the Stimpmeter, Frank Thomas, who served as its Technical Director, redesigned it, making the Stimpmeter a 36-inch device with a flat groove where the ball rested. In the four decades leading up to the Stimpmeter’s inception, Trostel says Stimpson, who was 80 when he died in 1985, continuously worked with USGA officials.

When it was released, the USGA referred to the device as the “USGA Speed Stick.” Two years later, the device was updated to be made out aluminum and also the name was officially changed to Stimpmeter in honor of the inventor.

Over the next 35 years, no changes were made to the Stimpmeter. As time passed, the Stimpmeter gained momentum, with virtually every club using it—or some other similar tool—today, Trostel said. (The Stimpmeter retails for $120.)

In 2013, Quintavalla updated the Stimpmeter, making a change he said was “fundamentally found by accident.” At the time, Quintavalla said the USGA was improving its understanding of how the ball rolls on turf, so it experimented with different Stimpmeter lengths.

From there, USGA officials discovered that there was a constant relationship between a standard length roll and shortening the distance of the roll. Meaning, if the short roll was multiplied to get back to a standard roll, the Stimps would line up.

The two-sided Stimpmeter, featuring a second notch to produce a half-length roll, follows the same calculation method. However, the result is multiplied by two to account for the shorter distance.

Because it’s essential for Stimp readings to be done on a flat surface, and some greens have a lot of slope or undulation, it was sometimes difficult to conduct precise tests, Bevard said. Now, Quintavalla’s updated version has allowed Stimpmeter readings to become more precise since they can be determined in a smaller area.

Since its inception, the Stimpmeter has served as a pioneer in providing information about how a golf course is playing on a given day. With new creations, like the USGA’s GS3 smart ball, that practice is continuing to evolve.

And still, 90 years after its birth stemmed from Sarazen’s bunker putt at Oakmont, the Stimpmeter is as relevant as ever heading into the 2025 U.S. Open.