How to calculate a USGA Golf Handicap Index

See the “HCP Index” next to your name on the Deemples app? Wonder how this number if calculated from the scores you have submitted on the app. Here we’ll show you how a USGA Golf Handicap Index (HCP Index) is calculated.

Formula to Calculate Handicap Index

Handicap Index = Average of your qualified Handicap Differentials * 0.96

2 questions here:

1. How do you calculate Handicap Differentials?
2. Which Handicap Differentials qualify for Handicap Index calculations?

1. Formula to calculate Handicap Differential per game

Handicap Differential = (Adjusted Gross Score – Course Rating) * 113 / Slope Rating

More questions here:

1. What is Adjusted Gross Score (AGS)?
2. What is Course Rating?
3. What is Slope Rating?

What is Adjusted Gross Score

Gross Score = Sum of your scores for each hole.

Adjusted Gross Score however, takes into account Equitable Stroke Control (ESC) where the maximum allowable score per hole for handicapping purposes is dependent on your course handicap. See the following table:

Course Handicap	Maximum Allowable Score Per Hole
<10	Double Bogey (+2)
10-19	7
20-29	8
30-39	9
>39	10

Course Handicap = Slope rating / 113 * Handicap Index

Course Rating and Slope Rating

Course Rating and Slope Rating are numbers that are available on the score card that show a difficulty of a golf course from a specific tee box in relation to another tee box of the same golf course or any other golf courses using the same USGA rating system.

They usually look like this:

	Blue Tee (Men)	White Tee (Men)	Red Tee (Women)
Course Rating	71.7	68.9	71.4
Slope Rating	132	127	127

• Course Rating – the higher the number, the more difficult the golf course
• Slope Rating – the higher the number, the more difficult the golf course

If a woman plays off the White Tee box, they wouldn’t be using the Men’s course and slope rating numbers for the white tee, but the women’s rating instead. If these ratings are not available on the score card, check with the golf course.

Going back to how a Course Handicap is calculated, and let’s say for this example, we’re playing off the men’s blue tee box with a 13.9 HCP Index:

Course Handicap = 132 / 113 * 13.9

= 16.237 or 16 (rounding to the nearest whole number)

So since my Course Handicap is 16 from the blue tees at Kinrara Golf Club, for my Adjusted Gross Score, based on the table above, the maximum allowable score per hole for handicapping purposes, would be 7.

My Gross Score for the game is the sum of all my scores for each hole. Let’s say for this game my score for each hole was:

Hole	Gross Score	Adjusted Gross Score
1	5	5
2	9	7
3	5	5
4	5	5
5	6	6
6	5	5
7	7	7
8	4	4
9	4	4
10	5	5
11	5	5
12	4	4
13	6	6
14	9	7
15	7	7
16	4	4
17	4	4
18	6	6
	100	96

As you can see on hole 2 and hole 14, I had a 9, which both are 2 over the maximum allowable score for handicapping purposes. Therefore, my Adjusted Gross Score for this game is 96 for handicapping purposes, whilst my Gross Score is still 100 for competition purposes.

Net Score = Gross Score – Course Handicap

In a competition, my net score would be 100 – 16 = 84.

Back to Handicap Differentials

Handicap Differential = (Adjusted Gross Score – Course Rating) * 113 / Slope Rating

Now that we know what Adjusted Gross Score, Course Rating, and Slope Ratings are, for this example we use the numbers above.

The Handicap Differential for this game

= (96 – 71.7) * 113 / 132

= 20.8 (round to 1 decimal point from 20.802)

2. Which Handicap Differentials qualify for Handicap Index Calculations

Now that we know how to calculate the handicap differential for each game, it’s important to know which of the handicap differentials qualify for Handicap Index calculations.

Depending on the number of handicap differentials from games you have posted results for, the number of handicap differentials you use are different:

Number of games posted	Number of Differentials to be used
5-6	Lowest 1
7-8	Lowest 2
9-10	Lowest 3
11-12	Lowest 4
13-14	Lowest 5
15-16	Lowest 6
17	Lowest 7
18	Lowest 8
19	Lowest 9
20	Lowest 10

Let’s say for this example, we have played 7 games, and have 7 differentials to use. Including the 20.8 we had above, we also have:

Games Posted	Handicap Differentials
1	20.8
2	20.3
3	18.9
4	17.1
5	15.9
6	14.8
7	18.9

Based on 7 available differentials, and based on the table above that, the number of differentials used for handicap index calculation would be the lowest 2 = 14.8 and 15.9.

So based on:

Handicap Index = Average of your qualified Handicap Differentials * 0.96

My new Handicap Index

= (14.8 + 15.9)/2 * 0.96

= 14.736

Do not round this number, but remove the digits up to the tenth decimal.

So 14.736 becomes a handicap index of 14.7.

If the number ended up being 14.787, DO NOT round handicap index to 14.8, but again, remove digits to the tenth decimal, which will still give you a handicap index of 14.7.

DO NOT ROUND, but DROP digits to the nearest tenth decimal.

Migrating to World Handicap System (WHS)

Starting in 2020, some countries in the world are on a 2 year plan to migrate from their existing handicap systems to the World Handicap System (WHS). This effort is to standardise golf handicaps around the world, so everyone can compete on a level playing field.

For this to happen, there’s a few variables that have to be standardised, which mostly includes the difficulty levels of the golf courses. 2 measurements used a) Course Rating and b) Slope Rating, would have to be implemented for golf courses all around the world. With the USGA rated golf courses already have course and slope rating implemented, which is more than 50% of the world, the rest will follow suit.

Deemples Handicap System

This transition to WHS will take 2 years, until end 2021. For the time being Deemples will continue using the USGA method since it requires way less variables. Only 1) Adjusted Gross Score 2) Course Rating, and 3) Slope Rating for it to be accurately calculated.

We’ll do another update again when we switch over to WHS, which might be later down the road. Meanwhile, we kinda agree with: https://www.golfdigest.com/story/voices-the-flaw-in-the-new-world-handicap-system-dean-knuth

If you want to know about ‘Golf Handicap Score Submission’ on Deemples, Click here.