Dim NextTick As Date, t As Date
Sub StartClock()
t = Time
Call TickTock
End Sub
Private Sub TickTock()
Range("A1").Value = Format(Time - t, "hh:mm:ss")
NextTick = Now + TimeValue("00:00:01")
Application.OnTime NextTick, "TickTock"
End Sub
Sub StopClock()
Application.OnTime earliesttime:=NextTick, procedure:="TickTock", schedule:=False
End Sub
Sub Reset()
Call StopClock
Range("A1").Value = 0
End Sub