diff --git a/lib/guevara/nacha.rb b/lib/guevara/nacha.rb
index 8e0d57e..2913190 100644
--- a/lib/guevara/nacha.rb
+++ b/lib/guevara/nacha.rb
@@ -38,8 +38,10 @@ def total
     end
 
     def file_control
-      entry_count = total { |b| b.batch_control.attributes[:entry_count] }
-      block_count = entry_count + batches.size * 2 + 2
+      entry_count  = total { |b| b.batch_control.attributes[:entry_count] }
+      record_count = entry_count + batches.size * 2 + 2
+      block_count  = (record_count/10.0).ceil # Count of the number of blocks of 10 rows within the file. https://achdevguide.nacha.org/ach-file-details
+
       FileControl.new(
         batch_count:  batches.count,
         block_count:  block_count,
diff --git a/test/test_file_generation.rb b/test/test_file_generation.rb
index b73f9a8..4cf161c 100644
--- a/test/test_file_generation.rb
+++ b/test/test_file_generation.rb
@@ -12,7 +12,7 @@
 6271031001953ACCOUNT234      0000001600FD00AFA8A0F7   marge baker             1123456780000001
 705wellsville|KS|66092|101 2nd st|                                                 00010000001
 82000000020010310019000000001600000000000000   Ruby123                         123456780000001
-9000001000006000000020010310019000000001600000000000000                                       
+9000001000001000000020010310019000000001600000000000000                                       
 NACHA
   nacha = Guevara::Nacha.new sample_nacha
 
@@ -50,3 +50,39 @@
   nacha = Guevara::Nacha.new nacha_attributes
   assert lines(nacha).size > 10
 end
+
+test 'calculate block_count (22 lines => 3 block_count)' do
+  expected = <<NACHA
+101  12345678  123456781411281330A094101                Rubylit                   Zest       0
+5200rubylit                                Ruby123PPD  payments140918140921   1123456780000001
+6271031001953ACCOUNT234      0000001600FD00AFA8A0F7   marge baker             1123456780000001
+705wellsville|KS|66092|101 2nd st|                                                 00010000001
+82000000020010310019000000001600000000000000   Ruby123                         123456780000001
+5200rubylit                                Ruby123PPD  payments140918140921   1123456780000002
+6271031001953ACCOUNT234      0000001600FD00AFA8A0F7   marge baker             1123456780000001
+705wellsville|KS|66092|101 2nd st|                                                 00010000001
+82000000020010310019000000001600000000000000   Ruby123                         123456780000002
+5200rubylit                                Ruby123PPD  payments140918140921   1123456780000003
+6271031001953ACCOUNT234      0000001600FD00AFA8A0F7   marge baker             1123456780000001
+705wellsville|KS|66092|101 2nd st|                                                 00010000001
+82000000020010310019000000001600000000000000   Ruby123                         123456780000003
+5200rubylit                                Ruby123PPD  payments140918140921   1123456780000004
+6271031001953ACCOUNT234      0000001600FD00AFA8A0F7   marge baker             1123456780000001
+705wellsville|KS|66092|101 2nd st|                                                 00010000001
+82000000020010310019000000001600000000000000   Ruby123                         123456780000004
+5200rubylit                                Ruby123PPD  payments140918140921   1123456780000005
+6271031001953ACCOUNT234      0000001600FD00AFA8A0F7   marge baker             1123456780000001
+705wellsville|KS|66092|101 2nd st|                                                 00010000001
+82000000020010310019000000001600000000000000   Ruby123                         123456780000005
+9000005000003000000100051550095000000008000000000000000                                       
+NACHA
+  batches = 5.times.map do
+    sample_batch
+  end
+  nacha_attributes = sample_nacha.merge(:batches => batches)
+
+  nacha = Guevara::Nacha.new nacha_attributes
+  nacha.to_s.lines.to_a.each_with_index do |line, index|
+    debugger_equal line, expected.lines.to_a[index]
+  end
+end