diff --git a/components/fpspreadsheet/fpsfunc.pas b/components/fpspreadsheet/fpsfunc.pas
index a587d4359..f17407d8a 100644
--- a/components/fpspreadsheet/fpsfunc.pas
+++ b/components/fpspreadsheet/fpsfunc.pas
@@ -128,6 +128,7 @@ function fpsYEAR        (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsAVEDEV      (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsAVERAGE     (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsCOUNT       (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsCOUNTBLANK  (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsMAX         (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsMIN         (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsPRODUCT     (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
@@ -1414,6 +1415,31 @@ begin
     Result := CreateNumber(Length(data));
 end;
 
+function fpsCOUNTBLANK(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// COUNTBLANK( range )
+// counts the number of empty cells in a range.
+var
+  arg: TsArgument;
+  r, c, n: Cardinal;
+  cell: PCell;
+begin
+  arg := Args.Pop;
+  case arg.ArgumentType of
+    atCell:
+      if arg.Cell = nil then Result := CreateNumber(1) else Result := CreateNumber(0);
+    atCellRange:
+      begin
+        n := 0;
+        for r := arg.FirstRow to arg.LastRow do
+          for c := arg.FirstCol to arg.LastCol do
+            if arg.Worksheet.FindCell(r, c) = nil then inc(n);
+        Result := CreateNumber(n);
+      end;
+    else
+      Result := CreateError(errWrongType);
+  end;
+end;
+
 function fpsMAX(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 // MAX( number1, number2, ... number_n )
 var
diff --git a/components/fpspreadsheet/fpspreadsheet.pas b/components/fpspreadsheet/fpspreadsheet.pas
index 98e0fda6e..2a98c9b1d 100755
--- a/components/fpspreadsheet/fpspreadsheet.pas
+++ b/components/fpspreadsheet/fpspreadsheet.pas
@@ -1195,7 +1195,7 @@ var
     (Symbol:'CHIINV';    MinParams:2; MaxParams:2;  Func:nil),   // fekCHIINV
     (Symbol:'COUNT';     MinParams:0; MaxParams:30; Func:fpsCOUNT),             // fekCOUNT
     (Symbol:'COUNTA';    MinParams:0; MaxParams:30; Func:nil),  // fekCOUNTA
-    (Symbol:'COUNTBLANK';MinParams:1; MaxParams:1;  Func:nil),   // fekCOUNTBLANK
+    (Symbol:'COUNTBLANK';MinParams:1; MaxParams:1;  Func:fpsCOUNTBLANK),        // fekCOUNTBLANK
     (Symbol:'COUNTIF';   MinParams:2; MaxParams:2;  Func:nil),   // fekCOUNTIF
     (Symbol:'MAX';       MinParams:1; MaxParams:30; Func:fpsMAX),               // fekMAX
     (Symbol:'MEDIAN';    MinParams:1; MaxParams:30; Func:nil),  // fekMEDIAN
diff --git a/components/fpspreadsheet/tests/testcases_calcrpnformula.inc b/components/fpspreadsheet/tests/testcases_calcrpnformula.inc
index 4109ee1b0..b90fa07a1 100644
--- a/components/fpspreadsheet/tests/testcases_calcrpnformula.inc
+++ b/components/fpspreadsheet/tests/testcases_calcrpnformula.inc
@@ -14,9 +14,10 @@
     RPNFunc(fekAdd, nil)))));
   SetLength(sollValues, Row+1);
   sollValues[Row] := CreateNumber(1.0+1.0);                     // B1 = 2
-// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-// DO NOT CHANGE THIS FORMULA - ITS RESULT (2) IS HARD-CODED IN OTHER TESTS !
-// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+  // don't refer to the cell contents here because they have not yet been calculated!
+{!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+!!  DO NOT CHANGE THIS FORMULA - ITS RESULT (-9) IS HARD-CODED IN OTHER TESTS !!
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!}
 
   // Subtraction
   inc(Row);
@@ -27,9 +28,10 @@
     RPNFunc(fekSub, nil)))));
   SetLength(sollValues, Row+1);
   sollValues[Row] := CreateNumber(1-10);                        // B2 = -9
-// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
-// DO NOT CHANGE THIS FORMULA - ITS RESULT (-9) IS HARD-CODED IN OTHER TESTS !
-// !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+  // don't refer to the cell contents here because they have not yet been calculated!
+{!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+!!  DO NOT CHANGE THIS FORMULA - ITS RESULT (-9) IS HARD-CODED IN OTHER TESTS !!
+!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!}
 
   // Add cell values - relative addresses
   inc(Row);
@@ -40,7 +42,6 @@
     RPNFunc(fekAdd, nil)))));
   SetLength(sollValues, Row+1);
   sollValues[Row] := CreateNumber(-7);
-// don't refer to the cell contents here because they have not yet been calculated!
 
   // Add cell values - absolute addresses
   inc(Row);
@@ -1124,11 +1125,11 @@
   inc(Row);
   MyWorksheet.WriteUTF8Text(Row, 0, '=COUNT(1, 1.1, 1.2, 0.9, 0.8)');
   MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
-   RPNNumber(1.0,
-   RPNNumber(1.1,
-   RPNNumber(1.2,
-   RPNNumber(0.9,
-   RPNNumber(0.8,
+    RPNNumber(1.0,
+    RPNNumber(1.1,
+    RPNNumber(1.2,
+    RPNNumber(0.9,
+    RPNNumber(0.8,
    RPNFunc(fekCOUNT, 5, nil))))))));
   SetLength(sollValues, Row+1);
   sollValues[Row] := CreateNumber(5);
@@ -1137,8 +1138,8 @@
   inc(Row);
   MyWorksheet.WriteUTF8Text(Row, 0, '=COUNT(B1:B2)');
   MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
-   RPNCellrange('B1:B2',
-   RPNFunc(fekCOUNT, 1, nil))));
+    RPNCellrange('B1:B2',
+    RPNFunc(fekCOUNT, 1, nil))));
   SetLength(sollValues, Row+1);
   sollValues[Row] := CreateNumber(2);
 
@@ -1146,8 +1147,8 @@
   inc(Row);
   MyWorksheet.WriteUTF8Text(Row, 0, '=COUNT(A1:B2)');
   MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
-   RPNCellrange('A1:B2',
-   RPNFunc(fekCOUNT, 1, nil))));
+    RPNCellrange('A1:B2',
+    RPNFunc(fekCOUNT, 1, nil))));
   SetLength(sollValues, Row+1);
   sollValues[Row] := CreateNumber(2);
 
@@ -1155,11 +1156,20 @@
   inc(Row);
   MyWorksheet.WriteUTF8Text(Row, 0, '=COUNT(B1:C2)');
   MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
-   RPNCellrange('B1:C2',
-   RPNFunc(fekCOUNT, 1, nil))));
+    RPNCellrange('B1:C2',
+    RPNFunc(fekCOUNT, 1, nil))));
   SetLength(sollValues, Row+1);
   sollValues[Row] := CreateNumber(2);
 
+  // COUNT
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=COUNTBLANK(A1:D2)');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNCellRange('A1:D2',
+    RPNFunc(fekCOUNTBLANK, nil))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(4);
+
   // MAX
   inc(Row);
   MyWorksheet.WriteUTF8Text(Row, 0, '=MAX(1, 1.1, 1.2, 0.9, 0.8)');