diff --git a/FemDesign.Core/Geometry/Point3d.cs b/FemDesign.Core/Geometry/Point3d.cs
index a14abe78..2c81cf96 100644
--- a/FemDesign.Core/Geometry/Point3d.cs
+++ b/FemDesign.Core/Geometry/Point3d.cs
@@ -173,8 +173,10 @@ public static bool ArePointsOnPlane(List<Point3d> points)
 
             for(int j = 0; j < points.Count; j++)
             {
-                bool IsOnPlane = (a * points[j].X + b * points[j].Y + c * points[j].Z + d) == 0;
-                if (IsOnPlane == true)
+                double IsOnPlane = a * points[j].X + b * points[j].Y + c * points[j].Z + d;
+
+                // check is IsOnPlane is within tolerance
+                if (Math.Abs(IsOnPlane) <= Tolerance.LengthComparison)
                     continue;
                 else
                     return false;