A countdown timer in VBA, for MS Excel. Copy-paste into a module in a .xlsm workbook.

CountdownTimer.bas

Dim updatingTimeNow As Date

Private Sub Auto_Open()
    ' Run as the workbook opens
    Call InitialiseTimer
End Sub

Private Sub SetUp()
    ' Run before anything else, independently
    Cells(1, 1) = "Countdown timer"
    Cells(2, 1) = "start time"
    Cells(3, 1) = "active time-formatted cell"
    Cells(4, 1) = "text conditional on timer"
    Cells(2, 2) = "00:00:30"
End Sub

Sub InitialiseTimer()
    Dim startTime As Range
    Set startTime = Application.ActiveSheet.Range("B2")
    Range("B3").Value = startTime
    Call Timer
End Sub

Sub Timer()
    updatingTimeNow = Now + TimeValue("00:00:01")
    Application.OnTime updatingTimeNow, "ResetTime"
End Sub

Sub ResetTime()
    Dim activeTime As Range
    ThisWorkbook.Activate
    Set activeTime = Application.ActiveSheet.Range("B3")
    activeTime.Value = activeTime.Value - TimeSerial(0, 0, 1)
    If activeTime.Value <= 0 Then
        ' MsgBox "Countdown complete."
        Range("B4").Value = "Countdown complete."
        Exit Sub
    Else
        Range("B4").Value = "Counting down ..."
    End If
    Call Timer
End Sub

Awesome, thank you.....:)

Hey ! Thank you for sharing your code ! It helped me a lot !

I ran into an issue when running your code as is on Excel 2019 : the countdown was slower than reality. But when I replaced activeTime.Value = activeTime.Value - TimeSerial(0, 0, 1) with activeTime.Value = activeTime.Value - TimeValue("00:00:01") this issue seems to be resolved.

Please let me know if you think, that it is a good solution :) !