Golf Simulator v2.2
High-fidelity putting trainer: read, aim, and pace in one workflow.
Drag the aim handle
Prioritize leave window control and tune pace around 17-inch past.
Green reading is one of the most critical skills in golf putting. It refers to analyzing the slope, speed, and grain of the putting surface before each stroke to determine the optimal aim direction and hitting force. Research shows that over 60% of strokes lost on the green by amateur golfers come from misreads rather than stroke mechanics issues (Arnold, 2002).
Professional golfers and top caddies systematically analyze every putt: first identifying the fall line — the direction a ball would naturally roll under gravity; then assessing the slope percentage to estimate break amount; and finally combining green speed (Stimp value) to determine precise aim angle and hitting force. This methodology is the foundation of our simulator's training system.
Our simulator uses Runge-Kutta 4th-order numerical integration (RK4) to calculate ball trajectories, accounting for gravitational components, rolling friction, and grain effects on ball speed. Every trajectory is based on peer-reviewed physics papers (Penner, 2002; USGA Technical Reports), ensuring that training gains transfer to real course conditions.
This simulator runs a complete physics engine in real time inside your browser. You set the green conditions — Stimp speed (4 to 18), slope percentage (0 to 8%), and slope direction — then choose your putt distance and aim angle. After clicking "Run Simulation," the engine calculates ball trajectory at 60 frames per second, rendering the ball path on an SVG canvas in real time.
After each simulation, the system evaluates your read accuracy (slope judgment), aim precision (target line selection), and speed control (pace judgment), giving each a score from 0 to 100. These three scores help you pinpoint training weaknesses: is it your read, your aim, or your pace? The training handbook provides targeted improvement suggestions based on your performance patterns.
The three-stage training curriculum progresses systematically: Stage 1 focuses on identifying the fall line and understanding slope percentage; Stage 2 teaches the Clock Face Method to convert reads into precise aim points; Stage 3 trains speed control, mastering the "17-inch rule" — finishing the ball 17 inches past the cup for optimal hole-out probability.
Whether you are a beginner just starting in golf, a mid-handicapper (5-15 range) looking to improve, or a low-handicap player preparing for competition, this simulator provides targeted training. Beginners can quickly build an intuitive understanding of green slope through visual slope arrows and instant trajectory feedback. Intermediate players can use the scenario challenges to systematically improve their reads and speed control. Advanced players can fine-tune technique under extreme conditions (high Stimp, steep slopes) and track long-term progress through data analytics. Our training system draws from PGA Tour caddie training methods, breaking complex green reading into quantifiable, trainable sub-skills.
The Stimp rating (Stimpmeter reading) measures green speed. It represents the distance (in feet) a ball rolls on the green after being released from a standardized ramp. Municipal courses typically range from 6-8, tournament greens from 11-13, and Masters-level greens can exceed 14. Higher Stimp means faster roll and more break — requiring more precise reads and gentler pace control.
The fall line is the direction a ball would naturally roll at any point on the green under pure gravity (ignoring initial momentum). It represents the steepest slope direction. Identifying the fall line is the first step in reading a putt because it determines the fundamental direction of break. Putting from above the fall line, the ball curves downhill; from below, it curves uphill. Our simulator clearly marks the fall line with directional arrows.
Dave Pelz's research found that a putt speed that would finish approximately 17 inches (43 cm) past the cup provides the maximum hole-out probability window. Too slow and gravity pulls the ball offline before it reaches the cup; too fast and the ball runs past. The 17-inch speed is the optimal balance between "enough speed to hold the line over the front edge" and "not so much that it blows past the back edge." Our simulator's pace control scoring is based on this standard.
Our physics engine is based on papers by Arnold (2002) and Penner (2002) published in the American Journal of Physics, using RK4 (4th-order Runge-Kutta) integration to solve the equations of motion. The model includes gravitational slope components, Stimp-calibrated rolling friction coefficients, directional grain effects on friction, and a USGA-standard cup capture speed model. While it cannot perfectly replicate every subtle undulation of a real green, it provides a training environment that closely mirrors real-world physics in the relationships between slope, speed, and break amount.
Challenge Mode provides preset green scenarios that test your reading ability under specific conditions. Each scenario sets a fixed Stimp value, slope, and distance, and you need to choose the correct aim direction and hitting force. The system scores you based on the deviation between your choices and the physics-calculated optimal solution. You can share challenge links with friends to compete on the same scenarios and compare green reading skills.
Yes, all putting records (including scores, scenario parameters, and timestamps) are saved in your browser's localStorage. This means your data is completely private and never uploaded to any server. You can view detailed statistics, trend charts, and personal bests on the Progress page. We also support exporting training data as CSV files for further analysis.
Dive deeper into putting physics, green reading techniques, and speed control methods. Each article combines scientific research with practical experience to help you build a systematic training mindset.
Master slope analysis, break estimation, and the AimPoint method with physics-backed drills.
Read →Everything you need to know about the Stimpmeter and how green speed affects your putting strategy.
Read →A systematic professional method used by PGA caddies for precise aim communication.
Read →Suree Golf Lab is dedicated to improving golf putting training through scientific methods. Our team combines physics research, software engineering, and golf instruction experience to create this free online green reading simulator. We believe that understanding the physics of ball motion on the green — rather than blind repetition — is the most efficient path to better putting.