FAQs

No — they are two separate parameters.
The club’s MOI (Moment of Inertia) refers to the entire club — that is, the assembled head, shaft, and grip. The higher the MOI, the more force is required to accelerate the club during the swing.
The clubhead MOI, on the other hand, applies only to the head itself. This parameter mainly affects the club’s forgiveness — how straight the ball flies on off-center hits — and it does not determine the overall MOI of the club.

Unfortunately, no. These two club parameters are calculated in completely different ways and must be determined independently.
In most cases, increasing the swingweight will also increase the MOI, but there is no simple conversion formula between them.
The opposite situation is also possible — for example, increasing the grip weight will lower the swingweight while slightly increasing the club’s MOI.

Yes, the length of the club (shaft) affects both the swingweight and the club’s MOI.

As a rough guideline:

• For irons, a 1-inch change in length alters the swingweight by approximately 6 points.
• For drivers, a 1-inch change in length alters the swingweight by approximately 5 points.

For precise calculations, use the calculator available in the Swingweight Adjustment section.

Yes, the shaft weight affects both the swingweight and the club’s MOI. Although its influence is weaker than that of the clubhead weight, it should not be ignored in calculations.

As a rough guideline:

• For irons, a 20-gram change in shaft weight alters the swingweight by approximately 1 point.
• For drivers, a 13-gram change in shaft weight alters the swingweight by approximately 1 point.

For precise calculations, use the calculator available in the Swingweight Planning section.

Swingweight can be measured using specialized swingweight scales. This method is quick and is typically used by professional clubfitters.
However, it is also possible to measure swingweight at home using common household tools — a scale and a ruler — and then easily calculate the final value.
A full description of this method, along with a dedicated calculator, is presented in the Swingweight Measurement section.

Yes — and it’s not as uncommon as it might seem. Even after a round played better than your current Handicap Index, the Index may still go up.

Remember that your Handicap Index is calculated based on your most recent 20 scores. Each new score enters the record, and the oldest of the 20 drops out.
So, if your latest round is good but not as good as the oldest score being replaced, your Handicap Index can actually increase.

In golf calculations, fractions are always rounded using the rule that “.5 rounds up.”
That means:

•  1.500     —> 2
•  1.4999   —> 1
•  1.250     —> 1.3
•  1.2499   —> 1.2

However, it’s important to remember that “up” means toward the higher value, not away from zero.
For negative numbers, this means:

•  -1.250   —> -1.2
•  -1.2501 —> -1.3

This applies to the calculations of the Course Handicap, Playing Handicap, and Score Differential.

The expected score on the second nine for a 9-hole round is necessary to calculate the 18-hole Score Differential for that round. The method for calculating the Score Differential is outlined in Rule 5.1 of the Rules of Handicapping. Unfortunately, neither the R&A nor the USGA publishes a formula for calculating the expected score.

Those interested in such calculations can:

• use the ready-made calculator available in the Handicap Differential tab, or
• develop the formula yourself using an existing calculator and “reverse engineering”.

The Rules of Handicapping require that, before obtaining an official WHS Handicap Index (Initial Handicap Index), the following be played and posted:

• one 18-hole or 9-hole round in EGA member countries
• three 18-hole rounds or six 9-hole rounds in other countries

Outside EGA member countries, a combination of 18-hole and 9-hole rounds is also permitted, for a total of 54 holes.

The Handicap Index is meant to represent a player’s ability as accurately as possible. Therefore, it is expressed to one decimal place.
In contrast, the Course Handicap and Playing Handicap indicate the number of extra strokes a player receives for a specific round of golf. For this reason, these values are rounded to whole numbers. After all, it’s impossible to take a fraction of a stroke (for example, 0.2 of a stroke).

In golf calculations, fractions are always rounded using the rule that “.5 rounds up.”
That means:

•  1.500     —> 2
•  1.4999   —> 1
•  1.250     —> 1.3
•  1.2499   —> 1.2

However, it’s important to remember that “up” means toward the higher value, not away from zero.
For negative numbers, this means:

•  -1.250   —> -1.2
•  -1.2501 —> -1.3

This applies to the calculations of the Course Handicap, Playing Handicap, and Score Differential.

The expected score on the second nine for a 9-hole round is necessary to calculate the 18-hole Score Differential for that round. The method for calculating the Score Differential is outlined in Rule 5.1 of the Rules of Handicapping. Unfortunately, neither the R&A nor the USGA publishes a formula for calculating the expected score.

Those interested in such calculations can:

• use the ready-made calculator available in the Handicap Differential tab, or
• develop the formula yourself using an existing calculator and “reverse engineering”.

A Net Double Bogey is the maximum score on a hole that is used when calculating the Adjusted Gross Score. The term double bogey itself means two strokes over par for a hole — for example, 6 on a par-4 or 5 on a par-3.

To calculate a Net Double Bogey, you add to the double bogey the number of handicap strokes the player receives on that particular hole based on their Course Handicap.

Examples:

• If the player receives one handicap stroke on a par-4 hole:
  4 (par) + 2 (double bogey) + 1 (handicap stroke) = 7
• If the player receives two handicap strokes on a par-5 hole:
  5 (par) + 2 (double bogey) + 2 (handicap strokes) = 9