diff --git a/app/routers/games.py b/app/routers/games.py
index 9314e3d..9c20047 100644
--- a/app/routers/games.py
+++ b/app/routers/games.py
@@ -331,11 +331,15 @@ async def create_game(request: Request, holes_count: int = Form(...),
         playing_handicap = None
         strokes_allocation_json = None
         par_for_formula = course_par_played * 2 if nine_of_eighteen else course_par_played
+        # Dedicated 9-hole courses have 9-hole ratings: WHS uses HI÷2 in the formula.
+        # For 9-of-18 the full HI is used and the result halved instead.
+        nine_hole_dedicated = (holes_count == 9 and not nine_of_eighteen)
         if hc is not None and tee_id and par_for_formula:
             async with db.execute("SELECT slope, rating FROM course_tees WHERE id = ?", (tee_id,)) as c:
                 tee_row = await c.fetchone()
             if tee_row:
-                ph = round(hc * (tee_row["slope"] / 113) + (tee_row["rating"] - par_for_formula))
+                hc_for_formula = hc / 2 if nine_hole_dedicated else hc
+                ph = round(hc_for_formula * (tee_row["slope"] / 113) + (tee_row["rating"] - par_for_formula))
                 playing_handicap = round(ph / 2) if nine_of_eighteen else ph
                 if hole_rank and playing_handicap > 0:
                     base, extra = divmod(playing_handicap, n_si)
diff --git a/app/templates/games/new_game.html b/app/templates/games/new_game.html
index 9dc54db..678ee9c 100644
--- a/app/templates/games/new_game.html
+++ b/app/templates/games/new_game.html
@@ -67,10 +67,13 @@
          const course = COURSES_DATA.find(c => c.id === this.courseId);
          if (!course || !tee || player.handicap == null) return null;
          const nineOfEighteen = parseInt(this.holesCount) === 9 && course.holes === 18;
-         // For 9-of-18, use par_9×2 as the 18-hole par so back-nine holes don't need to be in DB.
+         const nineHoleDedicated = parseInt(this.holesCount) === 9 && course.holes === 9;
+         // For 9-of-18: use par_9×2 as the 18-hole par, compute full CH then halve.
+         // For dedicated 9-hole: WHS formula uses HI÷2 directly with 9-hole ratings.
          const par = nineOfEighteen ? course.par_9 * 2 : course.par;
          if (!par) return null;
-         const ph = Math.round(player.handicap * (tee.slope / 113) + (tee.rating - par));
+         const hcForFormula = nineHoleDedicated ? player.handicap / 2 : player.handicap;
+         const ph = Math.round(hcForFormula * (tee.slope / 113) + (tee.rating - par));
          return nineOfEighteen ? Math.round(ph / 2) : ph;
        },
        goToConfirm() { this.step = 3; },