I found great VBA code online for a countdown timer that fits my need
perfectly. He http://www.vbaexpress.com/kb/getarti...b_id=478#instr

I'm a beginner when it comes to writing code and can use some help tweaking
it for my needs. I would like to do 2 things with the code:
1. Keep the whole thing on one sheet (i.e. start and stop button and inputs
on one sheet).
2. Change the countdown format display in mm:ss format.

Here is the code without going to the website:

Sheet1
________
Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)
Public Status As Boolean

Private Sub cmdStart_Click()
Status = True
Dim WarningTime As Integer
Dim Period As Double
Dim MyTime As Double

With Sheets("Main")
If (.Cells(5, 1) = "") Then
WarningTime = .Cells(5, 4)
Else
WarningTime = .Cells(5, 1)
End If

If (.Cells(8, 1) = "") Then
Period = .Cells(8, 4)
Else
Period = .Cells(8, 1)
End If
End With

If (Period < 0.01) Then Period = 0.01

With Sheets("Counter").Cells(2, 1)
.FormatConditions.Delete
.FormatConditions.Add xlCellValue, xlLessEqual, WarningTime
With .FormatConditions(1).Font
.Bold = True
.ColorIndex = 3
End With
.NumberFormat = Choose(Log(Period) / Log(10) + 3, "0.00", "0.0", "0")

.Value = Sheets("Main").Cells(2, 1).Value + Period
Sheets("Counter").Activate
While (.Value Period And Status)
.Value = .Value - Period
MyTime = .Value
For i = 1 To 100 * Period
Sleep 10
MyTime = MyTime - 0.01
If (MyTime <= 0) Then Exit For
DoEvents
Next i
Wend
If (.Value <= Period) Then .Value = "Time Up!"
End With
End Sub

Private Sub Worksheet_Change(ByVal Target As Range)
If (Target.Row = 2 And Target.Column = 1) Then
Cells(5, 1).Value = Cells(5, 4).Value
End If
End Sub

Sheet 2
_________________

Private Sub cmdStop_Click()
Sheets("Counter").Cells(2, 1).FormatConditions.Delete
Sheets("Main").Status = False
Sheets("Main").Activate
End Sub