diff --git a/src/Tiebreaks.php b/src/Tiebreaks.php
index 3f4c8c7..11d7dcc 100644
--- a/src/Tiebreaks.php
+++ b/src/Tiebreaks.php
@@ -144,4 +144,20 @@ abstract class Tiebreaks extends Tournament
         $allratings = array_slice($allratings, $cut);
         return round(array_sum($allratings) / count($allratings));
     }
+
+    /**
+     * @param Player $player
+     * @param int $cut
+     * @return int
+     */
+    protected function calculateKoya(Player $player, int $cut = 50)
+    {
+        $tiebreak = 0;
+        foreach ($player->getPairings() as $plkey=>$plpairing) {
+            if (($plpairing->getOpponent()->getNoOfWins() / count($plpairing->getOpponent()->getPairings()) * 100) >= $cut) {
+                $tiebreak += $plpairing->getOpponent()->getNoOfWins();
+            }
+        }
+        return $tiebreak;
+    }
 }
diff --git a/src/Tournament.php b/src/Tournament.php
index 09e1107..1c8eac7 100644
--- a/src/Tournament.php
+++ b/src/Tournament.php
@@ -296,6 +296,9 @@ class Tournament extends Tiebreaks
             case Tiebreak::AroCut:
                 return $this->calculateAverageRating($player, 1);
                 break;
+            case Tiebreak::Koya:
+                return $this->calculateKoya($player);
+                break;
             default:
                 return null;
         }