Roll-Time Calculator
Estimate time to the cup and time until the ball stops. Select green speed, slope, and desired finishing distance.
Putting Performance Details
Measure Entry Speed At The Hole
The stopwatch measures travel time, not instantaneous ball speed. To estimate entry speed, mark two points a short, known distance apart, centered on the hole (for example 6 inches before and 6 inches after). Time the ball crossing those two marks using video, then divide distance by elapsed time.
Important: This is average speed across the segment, an approximation of speed at the hole. A shorter segment improves locality but needs high-frame-rate video for reliable timing. Do not use this method if the ball drops into the hole; use a flat target marker instead.
Field Calibration &Amp; Validation
Verified benchmark: Stimp 10 ft · 15 ft to hole · 2.5% uphill · 3.00 s to hole · 24 in past hole (17 ft total). This benchmark is retained and is not overwritten by new tests.
Add A Measured Putt
Additional measurements are saved on this device and compared with the model. They do not automatically change the formula.
Learn how roll time relates to distance control, then use the Calculator, Stopwatch, Metronome, and Challenges to practice. Advanced measurements are available in Coach Mode.
Learn Roll-Time Putting
A practical guide to predicting ball roll, training distance control, reading greens, and using Roll-Time Putting tools.
Select any topic below to expand it. You can open multiple topics at once.
The Roll-Time Concept
Putting is a relationship between distance, speed, and time. Roll time is the elapsed time from putter impact until the ball reaches a selected point (such as the hole) or comes to rest. These are two different measurements: time to the cup and time to stop.
On a fast green, a ball generally needs less initial speed to cover the same distance than on a slower green. Uphill, downhill, and sidehill slopes also affect the required speed, travel time, and break. There is no single correct time for every 10- or 20-foot putt.
Roll-Time Putting adds a measurable reference to traditional feel. The objective is to recognize and reproduce a useful roll-time pattern under comparable conditions.
Distance Control & Speed Awareness
Choose a distance and a desired finishing position. Predict how long the ball should take to reach the hole, then putt and compare your prediction with the measured result.
- Set the hole distance and assess green speed and slope.
- Choose a finishing-speed intention, such as stopping at the hole or rolling 12–24 inches past.
- Use the calculator for an estimated reference time.
- Visualize the ball's pace, make the stroke, and observe its finishing distance.
- Measure the time and repeat to reduce variation.
Coaching key: judge time and finishing distance together. Matching a time is not success if the ball finishes in the wrong place.
Green Reading & Break
Line and speed must be read together. A faster putt may require a different starting line than a slower putt on the same slope. As the ball slows, gravity has more time to influence its path, so break can become more noticeable late in the roll.
Identify the slope, choose an intended arrival speed, picture where the ball begins to curve, and select a starting line that matches that speed. Practice the same putt at different speeds to see how the path changes.
Sidehill training: watch both the ball's travel time and the amount of break. A roll-time target alone cannot determine the correct aiming line.
Putt Visualization & Pre-Shot Routine
Train your eyes and imagination to predict the entire roll—not just the starting direction.
- Read: assess slope, surface speed, and break.
- Choose: select the intended finishing speed and stopping point.
- See: picture the ball starting on line, slowing, breaking, and approaching the hole.
- Sense: anticipate the approximate travel time.
- Execute: let the stroke respond naturally to that picture.
- Evaluate: compare the actual roll with the intended speed, line, and finish.
As skill improves, this becomes a quick on-course routine rather than a lengthy calculation.
Training Progression
Baseline: On a fairly level green, hit 10 putts from 10 or 15 feet. Record roll time and where each ball stops.
Time awareness: Before each putt, predict its time to the cup. Compare prediction, measured time, and finish.
Variable distances: Move between short, medium, and long putts. Learn how appropriate roll speed and duration change.
Slope & break: Add uphill, downhill, and sidehill putts. Adjust both speed intention and starting line.
Transfer: On the course, use the visual routine without relying on a timer for every putt. Measure selectively during practice to check progress.
Using The App's Training Tools
Roll-Time Calculator: Estimate time to the cup and time to stop from distance, green speed, slope, and intended roll past the hole. Treat outputs as estimates to calibrate with real putts.
Target Roll Duration: Practice predicting and reproducing a target time.
Stopwatch: Time a putt manually, with sound-triggered start, or using a countdown. Manual reaction time and environmental noise can affect measurements.
Video Frame Marking: Select or record a video, then mark impact and the destination/stop frame. Timing precision depends on frame rate and marker accuracy.
Metronome: Train stroke rhythm using adjustable beats per minute and the displayed time between beats. Stroke tempo is not the same measurement as ball-roll duration.
Challenges & Results: Test consistency, save practice outcomes, and review trends.
Putting Data: Review available measurements such as ball speed, distance, skid, and roll percentage alongside intended stopping distance. Keep imported measurements distinct from stopwatch times unless shots are reliably matched.
How To Measure Improvement
Evaluate several related outcomes rather than a single number: finishing-distance error, time consistency on comparable putts, accuracy of time predictions, short/long tendencies, and line/speed coordination on breaking putts.
For meaningful comparisons, record the intended hole distance, desired roll past the hole, slope, and green conditions. A putt finishing past the cup may be exactly what you intended; score it against the chosen stopping target, not automatically against the hole.
Look for tighter patterns across repeated sessions and better decisions on the course—not merely a faster or slower roll.
The JKG Roll-Time Putting Philosophy
See the Roll. Feel the Speed. Trust the Stroke.
Measurement helps players understand the relationship between speed, time, distance, and slope. Visualization turns that information into a clear intention. Repetition helps transform the intention into instinctive performance.
Measure → Understand → Visualize → Execute → Evaluate → Repeat.
The purpose is not to replace feel with numbers. It is to use numbers to develop better feel.
Target Roll Duration
Develop distance control using slope, break, and a target time. The distance and green speed are shared with the Calculator.
Smart Roll-Time Measurement
Partner taps Start at impact and Stop when ball stops.
Record a new video using your device camera.
Entry Speed — Video Markers
Place two visible marks around the hole (for example, 6 inches before and 6 inches after). Pause the video as the ball crosses each mark, then tap its marker button. The app calculates the average ball speed across that segment automatically.
This is the average speed between the marks, not an instantaneous measurement. Use a straight segment centered on the hole and high-frame-rate video where possible. If the ball drops into the cup, use a flat marker instead.
Tap Start at impact and Stop when the ball comes to rest. Manual reaction time adds measurement error.
Putting Tempo Metronome
Train a consistent putting rhythm with an audible beep on every beat. Set the tempo in beats per minute (BPM) and see the exact time between beats.
Tap Start to enable audio. Each beat sounds once; adjusting BPM while playing updates the rhythm.
Training tip: one beep can mark the start of the backswing and the next a repeatable rhythm reference. For a two-beat stroke, the time between those reference points is 60 ÷ BPM seconds. Use device volume to adjust loudness.
Putting Challenges
Predict the roll duration, putt toward the target, time the actual roll, and record how far the ball finished from the target.
JKG Putting Data Analysis
Import individual putts, compare distance control with your intended target, and save player sessions on this device. Your imported measurements are preserved on this device.
Use a CSV file containing individual putts. Column names such as Total, Ball Speed, Launch Direction, Side, Skid Distance, Roll Percentage, Roll Speed, Speed Drop, and Effective Stimp are recognized. PDF reports and screenshots cannot be imported automatically.
Paste CSV Data / Manual Entry
For manual entry, use one Total distance per line, or paste a full table with column headings. Check the units in your source file; Total distances are interpreted as feet unless labeled otherwise.
Session Performance
Individual Putts
| # | Total (ft) | Error (ft) | Ball Speed | Launch Direction | Side | Skid | Roll % | Roll Speed | Speed Drop | Effective Stimp |
|---|
Saved Putting Sessions
Sessions are stored in this browser on this device. Export JSON for backup before clearing browser data or switching devices.
Player Results
| Date | Player | Target | Time | Leave | Conditions |
|---|
Settings
Player and Coach Experiences
Player: Learn, calculate, measure, practice, and review results without advanced analysis menus.
Coach: All Player tools plus Entry Speed & Calibration, Putting Data Analysis, detailed calculator metrics, and video entry-speed markers.
Use the Player / Coach switch above the menu to change modes. Your choice is saved on this device. Switching modes never deletes your results.
Coach Mode is an interface preference, not a password-protected account. Results are stored locally on this device unless you export them.
John King Golf — Contact &Amp; Coaching
John King, PGA
Install On Your Device
Host this app over HTTPS, open it in Safari on iPhone/iPad, then use Share → Add to Home Screen → Open as Web App. On supported desktop browsers, use the browser's Install option.
Privacy And Storage
Player names and results are saved only in this browser's local storage. They are not synced across devices. Export backups regularly; clearing browser data can erase records. Avoid entering sensitive player information.
Version 17 • Roll-Time Putting • Offline-ready after first successful hosted load.