diff --git a/tests/__init__.py b/tests/__init__.py
index f24514a..0a3def9 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -107,7 +107,77 @@ class TestNd2Parser(unittest.TestCase):
 
     def test_calculate_channel_ludicrous_values(self):
         nd2 = MockNd2Parser(['', 'GFP', 'dsRed', 'dTomato', 'lulzBlue', 'jimbotronPurple', 'orange'], list(range(31)), list(range(17)))
-        for i in range(1000):
+        for i in range(10000):
             for n, channel in enumerate(['', 'GFP', 'dsRed', 'dTomato', 'lulzBlue', 'jimbotronPurple', 'orange'], start=i*7):
                 self.assertEqual(Nd2Parser._calculate_channel(nd2, n), channel)
 
+    def test_calculate_z_level(self):
+        nd2 = MockNd2Parser([''], [0], [0])
+        for frame_number in range(1000):
+            result = Nd2Parser._calculate_z_level(nd2, frame_number)
+            self.assertEqual(result, 0)
+
+    def test_calculate_z_level_1c1f2z(self):
+        nd2 = MockNd2Parser([''], [0], [0, 1])
+        for frame_number in range(1000):
+            result = Nd2Parser._calculate_z_level(nd2, frame_number)
+            self.assertEqual(result, frame_number % 2)
+
+    def test_calculate_z_level_31c17f1z(self):
+        nd2 = MockNd2Parser(list(range(31)), list(range(17)), [0])
+        for frame_number in range(1000):
+            result = Nd2Parser._calculate_z_level(nd2, frame_number)
+            self.assertEqual(result, 0)
+
+    def test_calculate_z_level_2c1f2z(self):
+        nd2 = MockNd2Parser(['', 'GFP'], [0], [0, 1])
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 0), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 1), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 2), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 3), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 4), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 5), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 6), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 7), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 8), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 9), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 10), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 11), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 12), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 13), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 14), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 15), 1)
+
+    def test_calculate_z_level_2c3f5z(self):
+        nd2 = MockNd2Parser(['', 'GFP'], [0, 1, 2], [0, 1, 2, 3, 4])
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 0), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 1), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 2), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 3), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 4), 2)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 5), 2)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 6), 3)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 7), 3)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 8), 4)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 9), 4)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 10), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 11), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 12), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 13), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 14), 2)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 15), 2)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 16), 3)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 17), 3)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 18), 4)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 19), 4)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 20), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 21), 0)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 22), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 23), 1)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 24), 2)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 25), 2)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 26), 3)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 27), 3)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 28), 4)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 29), 4)
+        self.assertEqual(Nd2Parser._calculate_z_level(nd2, 30), 0)
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