diff --git a/cell.go b/cell.go
index e47edd6..912aa69 100644
--- a/cell.go
+++ b/cell.go
@@ -20,6 +20,12 @@ func (c CellPos) A1Notation() string {
   return fmt.Sprintf("%s%d", aRangeLetter(c.Col), c.Row + 1)
 }
 
+func (c CellPos) RangeForData(data [][]string) CellRange {
+  bottomLeft := CellPos{c.Row + len(data) - 1, c.Col + len(data[0]) - 1}
+
+  return CellRange{Start: c, End: bottomLeft}
+}
+
 type CellRange struct {
   Start CellPos
   End CellPos
diff --git a/cell_test.go b/cell_test.go
index 8889214..7dc762e 100644
--- a/cell_test.go
+++ b/cell_test.go
@@ -36,3 +36,36 @@ func TestCellPosA1Notation(t *testing.T) {
   }
 }
 
+var rangeTests = []struct{
+  topLeft CellPos
+  width int
+  height int
+  expected string
+}{
+  {CellPos{}, 1, 1, "A1:A1"},
+  {CellPos{}, 1, 2, "A1:A2"},
+  {CellPos{}, 2, 2, "A1:B2"},
+  {CellPos{0, 10}, 2, 2, "K1:L2"},
+  {CellPos{10, 3}, 2, 3, "D11:E13"},
+}
+
+func TestRange(t *testing.T) {
+  for _, tt := range rangeTests {
+    var data [][]string
+    for i := 0; i < tt.height; i++ {
+      var row []string
+      for j := 0; j < tt.width; j++ {
+        row = append(row, "1")
+      }
+      data = append(data, row)
+    }
+
+    got := tt.topLeft.RangeForData(data).String()
+
+    if got != tt.expected {
+      t.Errorf("Wanted %s, but got %s for %+v, table: %v", tt.expected, got, tt, data)
+    }
+
+  }
+}
+
diff --git a/spreadsheet.go b/spreadsheet.go
index 34a1696..be5882f 100644
--- a/spreadsheet.go
+++ b/spreadsheet.go
@@ -91,7 +91,7 @@ func (s *Sheet) UpdateFromPosition(data [][]string, start CellPos) error {
     converted = append(converted, strToInterface(row))
   }
 
-  cellRange := DefaultRange(data)
+  cellRange := start.RangeForData(data)
 
   sheetRange := fmt.Sprintf("%s!%s", s.Title(), cellRange.String())
 
diff --git a/spreadsheet_test.go b/spreadsheet_test.go
index ce3eee9..a1780ca 100644
--- a/spreadsheet_test.go
+++ b/spreadsheet_test.go
@@ -19,7 +19,7 @@ var tsvTests = []struct {
 
 func TestTsvToArr(t *testing.T) {
   for _, tt := range tsvTests {
-    got := TsvToArr(strings.NewReader(tt.data))
+    got := TsvToArr(strings.NewReader(tt.data), "\t")
     if len(got) != len(tt.result) {
         t.Errorf("For \n%s\n, mismatched rows. wanted %v, but got %v", tt.data, tt.result, got)
     }