Tennis MGR/I Calculator
The MGR/I (Modified Gravity Ratio / Inertia) determines how easy it is to time the ball with a tennis racket. It strongly influences stroke mechanics, contact point, and confidence in high-pressure situations.
📘 What is Tennis MGR/I? (Click to Open)
The Origin of MGR/I
MGR/I originates from the physical pendulum model. It relates the racket’s mass distribution to its angular frequency, which determines how naturally the racket moves through the strike zone.
The core relationship:
MGR/I = (m · g · R) / I
Where:
- m = racket mass
- g = gravity constant
- R = balance point
- I = swingweight
Units are normalized so tennis rackets typically fall between ~20.0 and 21.5.
High vs Low MGR/I Explained
High MGR/I (Above ~21)
- Stroke feels like pushing through contact
- Easier early contact in front of the body
- Better depth control and ball feel
- More confidence under pressure
- Flatter, penetrating shots
Low MGR/I (Below ~21)
- Stroke feels like pulling the racket
- Easier to loop and spin the ball
- Harder to control depth and direction
- Timing suffers when tightening up
Real-World Player Examples
Roger Federer
MGR/I ≈ 21.17 — effortless timing, early contact,
exceptional precision.
Grigor Dimitrov (pre-2018)
MGR/I ≈ 20.25 — similar technique, but required more effort.
Nick Kyrgios
High MGR/I explains his natural timing and fluid service motion,
despite lower swingweight.
Disclaimer: MGR/I is an empirically derived performance indicator. It is not a strict scientific rule, but a highly useful practical model.