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How to Track Shooting by Court Zone
Manesh Jayawardhana
CIO & Co-founder
Eight from fifteen in the corner is 53%, which looks like a strength worth building an offence around.
Fifteen attempts is not enough to distinguish a 53% shooter from a 35% shooter. The margin of error on fifteen shots is wide enough to swallow most of the differences you would act on.
Sample size is the whole problem with shot charts
A shooting percentage from a small number of attempts carries a lot of noise. That noise does not average out by being displayed as a confident number on a chart.
Roughly, the uncertainty in a proportion shrinks with the square root of attempts. Practically:
| Attempts in a zone | Reading |
|---|---|
| Under 25 | Noise — do not act on it |
| 25-50 | Weak signal |
| 100 | Usable |
| 200+ | Stable |
That has a design consequence: fewer zones reach a usable sample faster. Fourteen detailed zones on a season’s data may leave every one underpowered, while five broad zones on the same shots give five readable numbers.
Start with fewer zones. Split them once the attempts justify it.
Effective field goal percentage
Raw shooting percentage treats every made shot as equal, which undervalues three-point shooting by exactly the amount a three-pointer is worth more.
eFG% = (FG made + 0.5 × 3P made) ÷ attempts
A 35% three-point shooter and a 50% two-point shooter score the same points per attempt — 1.05 against 1.00, in fact the three-point shooter slightly more. Raw percentage says the two-point shooter is far better. Effective field goal percentage says they are comparable, which is the true statement.
Any zone comparison that spans the arc has to use the weighted version, or it will recommend the wrong shots.
Log the bad attempts too
The most common way a personal shooting log becomes useless.
Recording only shots taken in rhythm, or only in structured drills, or stopping when the session goes badly, produces a chart that describes your best conditions rather than your shooting.
Game percentages are always lower than practice percentages — shots are contested, taken under fatigue, and often not the shot you wanted. A practice log that excludes bad attempts widens that gap further and makes the chart actively misleading about what to expect.
Everything gets recorded, or the numbers describe something other than what you think.
Track the context, not just the outcome
A made or missed shot is the least informative thing about an attempt.
Three fields turn a shot chart into something coachable:
Contested or open. A 40% figure on contested shots and a 40% figure on open shots mean very different things, and the second is a much bigger problem.
Off the dribble or off the catch. These are different skills with different mechanics, and a player strong at one can be weak at the other from the same spot on the floor.
Early or late in the session. Percentages that hold up through fatigue and percentages that collapse point at conditioning rather than shooting.
Recording three extra taps per attempt is more work, and it converts a chart that says where you miss into one that says why.
Chart efficiency, not just accuracy
A zone’s percentage is only half of what makes a shot good.
Points per attempt combines the percentage with the shot’s value, and it is what actually ranks zones. A 35% three-pointer produces 1.05 points per attempt; a 48% mid-range two produces 0.96. The lower percentage is the better shot.
That single comparison explains most of how shot selection has changed in basketball over the past two decades, and it is invisible in a chart showing raw percentages.
Free throws generated is the other missing term, since drives produce fouls that a shot chart does not record. A zone with a mediocre percentage that generates frequent free throws can be more productive than the chart suggests.
Common mistakes to avoid
- Acting on a zone with fewer than about 25 attempts.
- Using raw percentage across the three-point line.
- Recording only good attempts.
- Using detailed zones before there is enough data to fill them.
- Comparing practice percentages against game or published figures.
How to do it with Basketball Shot Chart Tracker
The Basketball Shot Chart Tracker flags zones with insufficient attempts.
- Choose a zone layout — fewer zones reach a usable sample faster.
- Record every attempt, including the ones taken out of rhythm.
- Read effective field goal percentage where zones cross the arc.
- Ignore any zone the tracker flags as under-sampled, which early on will be most of them.
Other sports tools are in the tools directory.
Frequently asked questions
How many attempts before a zone percentage means anything?
More than most people assume. Under about 25 attempts the margin of error exceeds the differences you would act on; around 200 the number becomes stable.
Why use effective field goal percentage?
Because a three-pointer is worth more. Raw percentage makes a 35% three-point shooter look worse than a 50% two-point shooter when they score about the same per attempt.
Do practice percentages predict game performance?
Not directly — game shots are contested and taken under fatigue, so game percentages are lower. The useful comparison is between your own zones, not between practice and games.
Final thought
Use five zones before fourteen. A chart with five readable numbers is worth more than one with fourteen that are all noise.