Golf Green Speed Calculator (Stimpmeter)

A Stimpmeter is a notched aluminum bar used to measure putting green speed. A golf ball is placed in the notch and the device is raised until the ball rolls out under gravity. The distance the ball travels across the green is recorded — the longer the roll, the faster the green. The USGA standardized the device in 1976 with a 30-inch notch height.

Measuring in both directions cancels out the effect of any slope on the green. The Stimp rating is the harmonic mean (Brede method) or simple average of the uphill and downhill distances, giving you a true flat-equivalent green speed regardless of the gradient of the test area.

Average public courses typically run between 6–8 feet. Private clubs and well-maintained courses often aim for 9–11 feet. Championship and tour conditions range from 12–14 feet, while elite venues like Oakmont during the U.S. Open can exceed 14–15 feet. Extremely fast greens above 13 feet are considered very difficult for most amateur golfers.

The Brede equation is a mathematical formula that uses the difference between uphill and downhill roll distances to calculate the slope of the testing surface. This allows green speed to be measured accurately on sections of green that are not perfectly flat, which is especially useful when a flat 10–14ft testing area cannot be found.

The USGA recommends three rolls in each direction (uphill and downhill) from the same starting position. Discard any rolls that deviate more than 8 inches (20 cm) from the average of the other two. Average the valid rolls in each direction before calculating the final Stimp rating.

Yes. Some devices use a shorter notch (approximately 15 inches) which produces roughly half the roll distance of the standard 30-inch USGA Stimpmeter. This calculator supports the '2X Compact' mode — it automatically doubles the measured distances so results are comparable to the standard Stimp scale.

Yes, significantly. Greens are typically slower in the morning due to dew and slower turf recovery after overnight temperatures. Heat and wind dry the surface and can increase speed throughout the day. For consistent benchmarking, the USGA recommends measuring in the afternoon under similar conditions each time.

Green speed measures how far a ball rolls, reflecting surface friction and grass height. Green firmness measures how much the surface resists ball impact on approach shots. Both matter for course setup — a firm, fast green is the hardest combination for players to hold and putt on, as seen at courses like Oakmont.