What Is a GMAX Test and Why Is It Important to You


Monitoring your synthetic turf field throughout its life is key to ensure that it is performing the way it should, as well as playability and protecting your athletes. One component of field monitoring is conducting a GMAX test by a turf professional. A GMAX test measures impact attenuation – the ability of the playing surface to absorb the “shock”, or kinetic energy – from a collision, such as a player falling to the surface. The lower the GMAX rating, the more energy is absorbed by the surface. Alternatively, the higher the GMAX rating, the less energy is absorbed by the surface, meaning more energy is returned to the player.

Top 4 Reasons for GMAX Testing

  • Indicates safety levels & protects athletes
  • Drives maintenance recommendations 
  • Yields insights for replacement planning
  • Assures your field stays within industry guidelines

This test involves dropping a 20-lb, flat-ended missile, which represents an athlete’s impact with the surface. There are 10 typical locations on a field that are tested, many of which we refer to as “high-traffic areas.” These include midfield, goal lines, batter’s boxes, etc. The score at each location is documented, and then all location’s scores are pulled into an average for the entire field. GMAX scores should not exceed a score of 200 G’s according to ASTM, or a score of 165 G’s according to the Synthetic Turf Council. 

Having this test performed will provide you insight on your field’s playability and impact attenuation, and should results indicate action is required, a plan to address the matter can be put in place. If you have a synthetic turf field, the Synthetic Turf Council recommends that you schedule a GMAX test annually to monitor your field’s rating. Conducting a GMAX test will take around 60 minutes to complete and should be conducted with warm, fair weather.  

A GMAX test is included with every Motz365 Condition visit. Motz365 Condition is one of the many comprehensive maintenance offerings available through Motz365 Service


Cleo Montgomery
Experts in Fielding Dreams.

There’s nothing like seeing a field of dreams become a reality, especially when it’s been long-awaited by the community, dedicated fans, and aspiring athletes.

View Our Recent Projects