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Golf Balling

Short answer: When a driver hits a golf ball, the ball flattens noticeably for a fraction of a millisecond and then springs back. The coefficient of restitution (COR) measures how much speed survives that collision: 1 means a perfectly elastic bounce and 0 means none.

Because a livelier ball goes farther, golf's governing bodies cap it. In the USGA/R&A Initial Velocity test, a ball is fired at a rigid barrier at 143.8 ft/s. Its initial velocity is calculated from its COR and contact time, and a sample fails if four or more of 24 balls exceed 255 ft/s. Balls must also meet the 317-yard Overall Distance Standard. From January 2028, that test will be run at a 125 mph clubhead speed instead of 120 mph, which the USGA expects to cut the longest hitters' drives by about 13 to 15 yards.

VideoWrite-up4 sources

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What should you know about Golf Balling?

Quick facts. Each one stands alone and has a stable ID you can cite.

  1. The ball's limit is 250 ft/s initial velocity plus a 2% tolerance.

    DD-695-F01 · Write-up · Exhibit C (How the rules test it)

  2. From 2028, conformance testing uses a 125 mph clubhead speed.

    DD-695-F02 · Write-up · Exhibit E (The 2028 change)

Video transcript: Golf Balling: Squash, Then Spring

DID YOU KNOW? The elasticity of a golf ball refers to its ability to deform and then quickly return to its original shape when struck, which directly affects how much energy is transferred from the club to the ball. When the club face hits the ball the outer layers compress, storing energy, and then rapidly rebound propelling the ball forward. This property is measured by the coefficient of restitution, or COR, with higher elasticity producing greater launch speed and distance. NOW YOU KNOW!

Burned-in captions, read frame by frame (see transcript.md) · 24.1s Reel ·

Video coming soonGolf Balling · Instagram Reel
Golf Balling: Squash, Then Spring Instagram Reel · · 24.1s

The write-up

Squash, then spring. How fast a golf ball rebounds is capped by golf's rules.

  1. Exhibit A

    What COR measures

    COR is the ratio of rebound speed to impact speed. A value of 1 is a perfectly elastic collision, and lower values mean more energy is lost as heat and vibration.

  2. Exhibit B

    The whole ball deforms

    The core and cover compress together, not just the 'outer layers'. The ball flattens against the clubface during a contact lasting well under a millisecond, then springs back.

  3. Exhibit C

    How the rules test it

    The ball is fired at a rigid barrier at 143.8 ft/s. Its initial velocity is calculated from COR and contact time and compared with a 250 ft/s limit plus a 2% tolerance (255 ft/s).

  4. Exhibit D

    Distance cap

    Balls must also pass the 317-yard (plus 3-yard tolerance) Overall Distance Standard, tested with a mechanical golfer.

  5. Exhibit E

    The 2028 change

    From January 2028, the distance test moves from 120 mph to a 125 mph clubhead speed. The USGA estimates the longest hitters will lose 13 to 15 yards and most recreational golfers 5 yards or less. Recreational players can keep using older conforming balls until 2030.

Questions people ask about Golf Balling

What does COR compare?

Speed after the collision divided by speed before it.

Source: Write-up · Exhibit A (What COR measures) · Wikipedia: Coefficient of restitution

What initial-velocity limit do the rules set (before tolerance)?

250 ft/s, plus a 2% tolerance.

Source: Write-up · Exhibit C (How the rules test it) · USGA/R&A: Initial Velocity Test Protocol

What is the Overall Distance Standard?

317 yards, plus a 3-yard tolerance.

Source: Write-up · Exhibit D (Distance cap) · USGA (Dec 2023): Revised golf ball testing conditions to take effect in 2028; USGA: The Golf Ball and Distance, Frequently Asked Questions

What clubhead speed will the 2028 test use?

125 mph, up from 120 mph.

Source: Write-up · Exhibit E (The 2028 change) · USGA (Dec 2023): Revised golf ball testing conditions to take effect in 2028; USGA: The Golf Ball and Distance, Frequently Asked Questions

A COR of 1 would mean...

No speed would be lost.

Source: Write-up · Exhibit A (What COR measures) · Wikipedia: Coefficient of restitution

Test Your Knowledge

All quizzes →

5 questions, all from this case file. Answers are revealed instantly.

  1. What does COR compare?

    1. Rebound speed to impact speed
    2. Weight to size
    3. Spin to height
    4. Dimples to cover area
    Show the answer

    Answer: A. Rebound speed to impact speed Speed after the collision divided by speed before it. Source: Write-up · Exhibit A (What COR measures) · Wikipedia: Coefficient of restitution

  2. What initial-velocity limit do the rules set (before tolerance)?

    1. 150 ft/s
    2. 250 ft/s
    3. 350 ft/s
    4. 500 ft/s
    Show the answer

    Answer: B. 250 ft/s 250 ft/s, plus a 2% tolerance. Source: Write-up · Exhibit C (How the rules test it) · USGA/R&A: Initial Velocity Test Protocol

  3. What is the Overall Distance Standard?

    1. 317 yards
    2. 250 yards
    3. 400 yards
    4. 500 yards
    Show the answer

    Answer: A. 317 yards 317 yards, plus a 3-yard tolerance. Source: Write-up · Exhibit D (Distance cap) · USGA (Dec 2023): Revised golf ball testing conditions to take effect in 2028; USGA: The Golf Ball and Distance, Frequently Asked Questions

  4. What clubhead speed will the 2028 test use?

    1. 100 mph
    2. 120 mph
    3. 125 mph
    4. 150 mph
    Show the answer

    Answer: C. 125 mph 125 mph, up from 120 mph. Source: Write-up · Exhibit E (The 2028 change) · USGA (Dec 2023): Revised golf ball testing conditions to take effect in 2028; USGA: The Golf Ball and Distance, Frequently Asked Questions

  5. A COR of 1 would mean...

    1. A perfectly elastic bounce
    2. No bounce at all
    3. Twice the speed
    4. A broken ball
    Show the answer

    Answer: A. A perfectly elastic bounce No speed would be lost. Source: Write-up · Exhibit A (What COR measures) · Wikipedia: Coefficient of restitution

Cite this case file

Easterling, Marcus. "Golf Balling." The Detail Department (DetailEnjoyer), case file DD-695, last updated Jan 25, 2026. https://detailenjoyer.com/case/golf-balling/

Permalink: https://detailenjoyer.com/case/golf-balling/ · Last updated

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Cite a single fact by its ID, for example DD-695-F01 → https://detailenjoyer.com/case/golf-balling/#DD-695-F01

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