Golf handicap·78 · 55
78 · Slope Rating 55
12.3
Score Differential · ×2.055

78 on slope 55 — differential 12.3

Shooting 78 — 6 over par — on a slope-55 course gives a differential of 12.3. On a standard course the same round would read 6.

Adjusted gross score
78
Strokes over par
+6
Slope Rating
55
Slope factor
×2.055
Score Differential
12.3
On a standard course
6
Course Handicap
6

Same score, other courses

78 · 55
12.3
78 · 75
9
78 · 95
7.1
78 · 105
6.5
78 · 113
6
78 · 120
5.7
78 · 130
5.2
78 · 140
4.8
78 · 148
4.6
78 · 155
4.4

A bigger slope divides 113 by more, so the differential comes out smaller. Ninety strokes on a slope-155 course is a far better round than ninety on a slope-95 course. The rules allow slopes from 55 to 155, and most courses land between 105 and 145.

The formula is one multiplication

Differential = (adjusted gross score − Course Rating) × 113 ÷ Slope Rating. 113 is the slope of a course of standard difficulty, so on such a course the multiplier is exactly one and changes nothing. This table assumes a par-72 course rated 72.0, which isolates what the slope alone does.

One round is not an index

A Handicap Index is the average of the best eight differentials from your last twenty rounds. What this table gives is therefore not an index but **the differential a single round produces**. That averaging is also why one good day barely moves an index: only eight of twenty scores count, and the other twelve do nothing.

Nearby slopes

78 · 75
9

Same course, other scores

72 · 55
0
75 · 55
6.2
78 · 55
12.3
81 · 55
18.5
85 · 55
26.7
90 · 55
37
95 · 55
47.3
100 · 55
57.5
108 · 55
74
115 · 55
88.3

What this table assumes

It assumes a par-72 course rated exactly 72.0. Real courses rate above or below par, and that gap enters the arithmetic directly. The adjusted gross score is also capped hole by hole at net double bogey, so it can differ from what you actually wrote down, and a playing-conditions adjustment may be applied for the day.

How to read this

  • Differential = (gross score − Course Rating) × 113 ÷ Slope.
  • 113 is standard difficulty, so at slope 113 nothing changes.
  • The higher the slope — the harder the course — the better the same score reads.
  • A Handicap Index averages the best eight of your last twenty rounds.

Frequently asked questions

Q. What differential does 78 on slope 55 give?

12.3 — that is (78 − 72) × 113 ÷ 55.

Q. What is the slope factor?

113 ÷ 55 = 2.055, above one, so an easier course than standard.

Q. And on a standard course?

6. At slope 113 the strokes over par become the differential unchanged.

Q. Is this my handicap?

No. An index averages the best eight of your last twenty rounds; this round is only one candidate.