How PinFlag gets its numbers

Every number is strokes gained on Mark Broadie’s published baselines, the same framework professional golf uses. The tables are public, the formula is one line, and this page includes the places where the numbers stop being reliable. You should be able to check the arithmetic rather than take our word for it.

The formula

One line, and everything else follows from it.

strokes gained = expected strokes before − expected strokes after − strokes taken

A 150 yard approach from the fairway to 18 feet, worked through: the baseline says 2.945 expected strokes from where you started and 1.840 from where the ball finished. The shot itself cost one. So 2.945 less 1.840 less 1 is 0.105. That is the whole calculation, on every shot. Run it yourself on the calculator or read every row on the expected strokes table.

Where the baselines come from

Mark Broadie, a professor at Columbia Business School, built the expected strokes tables from tour data and published them in 2011. The PGA Tour adopted the framework, and it sits behind every credible strokes gained number in golf.

That has a consequence worth stating plainly. No golf app has a better version of this arithmetic, because the arithmetic is public. What separates one app from another is the quality of the lie and distance it is handed, and whether the number reaches you while you can still use it. Anyone describing proprietary strokes gained arithmetic is describing their input, not their maths.

Measured, Estimated, or a dash

Every number carries a label, on the number rather than in a footnote.

What each label on a PinFlag number means
Label	What it means	How it becomes Measured
Measured	Built from your own recorded data, on ground PinFlag can vouch for.	Already there.
Estimated	A population average standing in until your own data exists.	Log rounds, or import launch monitor carries so the distances are yours.
A dash	Waiting for data.	Never filled in with a guess.

How to read the numbers

Four things worth knowing about the published baseline, each of which the app handles for you.

The lie tables start at 20 yards; the green has its own table in feet. Rough at 5 yards reads 2.59 and rough at 20 reads 2.59, the same published number, so the app prices approach and tee shots from the lie tables and every putt from the putting table by the foot, where the source is dense. Short-game shots are priced from the lie they start in and the leave they produce, which is what separates a chip to 4 feet from a chip to 12.
A number before the swing is built on a dispersion pattern, and yours takes over as soon as it exists. The benchmark pattern models about ±9.0 yards at 150 and is labelled Estimated. Import a launch monitor session or log rounds and the pattern becomes your own, labelled Measured, and every target is priced on the spread you actually hit.
Zero is the tour average, and the lenses put the same shots on your scale. Nearly every amateur number is negative against a tour field, which is the scale working. Switch the benchmark lens to Scratch or a handicap level and the same shots are repriced against that table, so the gains and losses read relative to a golfer like you. The benchmark tables show the arithmetic.
The baseline prices the lie and the distance; you add the day. A two-club breeze or a green that falls away from you is yours to weigh, and the number gives you the exact price of each option so the weighing is done on strokes rather than on feel.

Course data, and where it lives

Course maps are professionally mapped and independently verified by PinFlag on site. They live in the app and only in the app: no course pages on this website, no course search, no hole maps published here. That is a deliberate boundary and it is not going to move.

Where the decision lives

PinFlag prices every target you consider and shows the number: the flag, the fat side of the green, the layup, each with your own dispersion and the lie read from the course. You add the wind, the lie under the ball and whether you need a birdie, and the choice is better for having both the arithmetic and the situation in front of you.

PinFlag is built for iPhone and launching on the App Store, with an Android list open. What it costs is stated in full, and the strokes gained explainer walks the framework through with a whole hole.

Frequently asked questions

Where do PinFlag’s strokes gained numbers come from?

Mark Broadie’s published expected strokes baselines, built from tour data and published in 2011, are the Tour benchmark and the default, priced at every yard and every foot between the published distances. The app can also frame your numbers against modeled scoring-level benchmarks (labeled Modeled, never called a handicap); those are derived by scaling the published tables, and every one of them is disclosed inside the app. The arithmetic is public, so what separates apps is the quality of the input, not the maths.

Is PinFlag accurate enough to trust for tournament preparation?

Yes. The arithmetic is exact and the baselines are published, and the app reads the lie from the course map and the distance from the pin you placed rather than asking you to type either. Where PinFlag is working from your own data it says Measured; where a benchmark stands in it says Estimated; and the number that prices the target before you swing is the number that grades the shot afterwards.

What is the difference between Measured and Estimated?

Measured means the number is built from your own recorded data on ground PinFlag can vouch for. Estimated means a population average is standing in until your data exists. The label sits on the number itself, not in a footnote, so you always know which one you are reading.

Does PinFlag need a launch monitor or sensors?

No hardware is required. PinFlag reads the lie from the course map and the distance from the pin you placed, and prices every target with a benchmark pattern labeled Estimated from your first round. Importing launch monitor carries or logging rounds makes the pattern yours and moves figures from Estimated to Measured.

How does PinFlag help me choose a club and a target?

By pricing every option you consider before you commit. Put the aim on the flag, the fat side of the green or the layup and read the strokes gained of each, with your own dispersion for that club and the lie read from the course; Shot Cloud draws your real pattern over the trouble. You add the wind, the lie under your ball and whether you need a birdie, and the decision is better for having both the arithmetic and the situation in front of you.

How does PinFlag define around the green, the benchmark lenses, and a penalty?

Around the green means within 30 yards of the HOLE, measured from where the ball lies; the PGA TOUR measures its around-the-green category from the edge of the green and Broadie’s short game runs to 100 yards, so category splits can differ from those sources while the total does not. A benchmark lens is a scoring average level relative to a modeled scratch golfer, labeled Modeled in the app; it is not a Handicap Index and is never called one. A penalty lie is priced with the rough table, plus the penalty stroke itself.

By The PinFlag Team.