Clegg Impact Hammer testing measures how hard a pitch hits back when a player lands on it. High Gmax values correlate directly with concussion, bone and joint injury — and every major sport now mandates limits.
Surface hardness is the single most important safety metric for a natural turf pitch. A surface that's too hard transmits impact force directly into the player's body — leading to stress fractures, concussions and ACL injuries. A surface that's too soft is a fatigue and traction problem.
The Clegg Impact Hammer is the governing-body-mandated tool for measuring this. A 2.25kg missile is dropped from 450mm through a vertical guide; accelerometers in the missile record the peak deceleration on impact as it strikes the surface. That reading, expressed in Gmax units, is the surface hardness value.
FIFA's quality threshold is 55–100 Gmax for match play. The FA uses 40–90 Gmax for professional natural turf under its Performance Quality Standard. Above 100, impact injury risk increases sharply. Below 40, the surface is functionally unstable.
Every step is UKAS-audited. The equipment is calibrated, the procedure is traceable, the data is defensible.
Every test we run is UKAS-accredited and defensible. Tell us about your venue and we'll come back with a fixed written quote within two working hours.
or email info@surfaceperformance.com with your venue and test requirements