Baseball Pitch Trajectory Simulator

See how any pitch moves through space — from release to the catcher’s glove

A free, browser-based tool that simulates the 3D trajectory of a pitched baseball using real physics. Search any MLB pitcher, pick a pitch, and watch it fly.

Launch the Simulator    Quick Start Guide

Simulator showing a pitch trajectory with orange spin path and cyan no-spin path

The simulator in action — Ohtani’s fastball trajectory with spin and no-spin comparison

What It Does

You type a pitcher’s name. The simulator pulls their actual pitch data from MLB Statcast — every four-seam fastball, slider, curveball, and changeup they threw. Data is available from 2016 to the current season. Pick any pitch, hit Simulate, and watch the ball travel from the pitcher’s hand to home plate in 3D.

The trajectory is not an animation based on video. It is a physics simulation. The ball’s path is computed from its release speed, spin rate, and spin axis using the same aerodynamic model developed by Prof. Alan Nathan at the University of Illinois — the standard reference for baseball trajectory research.

Why It Matters

For Pitching Coaches

Overlay a pitcher’s fastball and changeup to see if they tunnel effectively. See exactly where and when the two trajectories diverge.

For Analysts

Compare spin decomposition (backspin, sidespin, gyrospin) across pitchers. Get season-wide summaries with spin efficiency and BSG breakdown via the API. Export full trajectory data to CSV.

For Player Development

Enter Rapsodo measurements directly and simulate the resulting trajectory. Test “what if” scenarios by adjusting spin rate or axis.

Key Features

Feature Description
MLB Statcast Integration Search any pitcher, browse their game-by-game pitch data, simulate any individual pitch
Season Summary API Per pitch-type averages (speed, spin, movement, BSG, spin efficiency) and monthly trends in a single request
Multiple Input Modes Statcast data, manual sliders, or Rapsodo measurements
Overlay Comparison Stack multiple pitches to compare trajectories side by side
Batter’s Eye View First-person camera from the batter’s box — see what the hitter sees
Pitch Tunnel Visualize the tunnel point (23.8 ft) where the batter must decide
Spin Axis on the Ball Animated baseball with procedural seam texture, rotating at real angular velocity
CSV Import / Export Full trajectory data with velocity, acceleration, and force breakdown
Video Recording Export the 3D view as MP4
Shareable Links Each simulation generates a URL that recreates the exact same pitch in a browser
Claude Desktop (MCP) Query Statcast data and run simulations using natural language from Claude Desktop. Setup guide
Adjustable CL Model Choose between Statcast-fitted (cl2=1.045) or Nathan original (cl2=1.12) lift coefficients

Pitch Types at a Glance

The simulator uses the same pitch type classification and color coding as MLB Statcast:

FF 4-Seam Fastball   SI Sinker   FC Cutter   SL Slider   CU Curveball   CH Changeup   FS Splitter   ST Sweeper

How the Physics Works

The simulator solves the equations of motion for a spinning ball in air:

  • Drag force slows the ball down (opposing its velocity)
  • Magnus force pushes the ball sideways and/or upward, perpendicular to both the spin axis and the velocity
  • Gravity pulls the ball down (g = 9.80 m/s², MLB stadium average)

The spin is decomposed into three orthonormal components:

  • Backspin — rotation around the axis perpendicular to velocity in the horizontal plane. Creates “rise” (resists gravity). A four-seamer with 2200 rpm backspin drops about 40 cm less than a ball with no spin.
  • Sidespin — rotation around the axis perpendicular to both the velocity and the backspin axis. Creates horizontal movement.
  • Gyrospin — spin around the velocity direction (like a bullet). Does not create Magnus force. A pitch with high gyrospin and low backspin/sidespin will have less movement despite high total spin rate.

The BSG basis is orthonormal: eb = eg × eZ (horizontal), es = eb × eg, where eg is the velocity direction and eZ is vertical. This ensures clean decomposition with no leakage between components.

Ball parameters match Nathan’s Excel Trajectory Calculator: mass = 5.125 oz, circumference = 9.125 in.

The simulation uses 4th-order Runge-Kutta integration with 0.001-second time steps.

API Access

The simulator exposes a public REST API. Key endpoints:

Endpoint Description
POST /statcast/search Search for a pitcher by name
POST /statcast/games Get game dates for a pitcher/year
POST /statcast/pitches Get all pitches for a game date
POST /statcast/simulate Run trajectory simulation
POST /statcast/season_summary Season-wide pitch-type summary with BSG and monthly trends

No API key required. Base URL: https://baseball.skill-vis.com

For natural language access via Claude Desktop, see the MCP Server setup guide.

Credits