Everything you believe about putting is downstream of one number you've never seen.
It's not the line. It's pace — and almost nothing you think you know about a green survives contact with the physics. Let's prove it.
The hole is 4.25 inches wide — but only if the ball is barely moving.
Speed up the ball and the effective hole physically shrinks. This is why a putt can lip out from dead center and leave you cursing the golf gods. Drag the pace and watch the target you actually have to hit.
Show me the science
The hole "captures" the ball only if its speed at the front edge is below a ceiling — about 1.63 m/s for a 4.25″ cup (Penner / Holmes). Above that, the ball's momentum carries it across the opening faster than gravity can drop it the one ball-radius it needs to fall, so it skips the far lip.
Because a faster ball needs a longer drop-window, the effective capture width shrinks as pace climbs — from the full 4.25″ at die-in speed toward a sliver at ram speed. That shrinking target is exactly what the slider above is showing you.
Model: Penner, The Physics of Putting (Can. J. Phys., 2002) and B. Holmes' capture-speed work. Directions are exact; the specific ceiling models one hole geometry — real numbers vary with rim, ball and surface.
Set the green. Aim. Choose your pace. Watch the physics you can't see.
One correct engine — skid, roll, gravity, capture — running underneath. Break, lip-outs, and the perfect-pace window all emerge; nothing here is faked.
Read a putt without committing to a speed and you've read nothing.
Same slope. Same start. Only the pace changes — and the entire line changes with it. There is no single "right line," only line-and-pace pairs that work.
Every "true roll" putter ad is selling you something the physics won't allow.
The ball leaves your putter skidding, with backspin or near-zero spin — never the topspin pure roll needs. Friction spins it up over the first ~15–20%. You can't fix that. You can only make it consistent.
A Stimpmeter doesn't measure speed. It measures how far a ball rolls off a ramp — in feet.
That single number is the whole game. Your PrimePutt rolls at Stimp 10 — here's exactly what that means, and why a fixed stroke travels wildly different distances as greens get faster.
There is no perfect putt. There's the right pace for the line you chose — and the nerve to commit.
Five things you now know that most golfers never will:
The hole shrinks with speed
4.25″ → under 2″. Capture size is real.
You can't impart topspin
Every putt skids ~15–20% first. "True roll" is marketing.
Speed changes break
There's no single right line — only line + pace.
Face, not path (~85%)
You've been practicing the 17%.
The ball doesn't matter on the green
Soft vs firm changes feel, not roll. Grain is a Bermuda thing.
What's your Putting IQ?
0 / 5Your PrimePutt rolls at Stimp 10. Go dial your pace on the real thing.
Use the mat's 3-foot markers: hit three putts trying to finish exactly 17 inches past the cup. That's the pace that beats the lumpy donut and keeps the hole at full size. This tool taught the why — the mat is where it becomes muscle.
Get the mat PGA pros use →Sources: Penner, The Physics of Putting, Can. J. Phys. 80 (2002) · USGA/Holmes Stimpmeter · Quintic Ball Roll · Dave Pelz · Cure Putters · Golf Digest (capture size) · The Left Rough (grain).
That was Chapter 1. Five more to go.
You just finished pace & capture. Keep going in order — each chapter builds on the last — or jump to whatever's costing you strokes.