VBA - sum totals to a master worksheet - excel

Question

Okay, so here goes. I have a workbook with individual worksheets for each day detailing the stock trading activity. I also currently have a VBA which provides a sum total for specified columns on each of these worksheets, and this works fine.
However, what I would like to do is add to my VBA so that it provides a sum total for these columns into the master worksheet.
So, for example: If there was trading activity totalling 4m on the 1st Oct 2018 on worksheet 1, and trading activity totalling 3m on 2nd october 2018 on worksheet 2, I would like to have this total of 7m shown on the master worksheet.
I've attached my current vba below, the column currently being summed on each individual worksheet is J. The columns summed on the individual worksheet do not change, however the amount of data contained in those columns obviously does depending on trading activity.
Sub autoSum_AllSheets()
Dim ws As Worksheet
Dim cel1 As String, cel2 As String
Dim firstCel As Range
For Each ws In ActiveWorkbook.Worksheets
With ws
Set firstCel = .Range("J3").End(xlDown).Offset(2, 0)
cel1 = firstCel.Offset(-2, 0).End(xlUp).Address
cel2 = firstCel.Offset(-1).Address
firstCel.Value = "=SUM(" & cel1 & ":" & cel2 & ")"
End With
Next ws
End Sub
I've also attached a screenshot of a current mock worksheet taken from a random day, with the sum total i get after running the vba bolded and highlighted in red.
Any advice on how to approach this would be great as I'm a newcomer to all things VBA.
Edit: I've attached a mock screenshot of what I'm trying to achieve on the master worksheet below:

Answer 1

I recommend the following …
Option Explicit
Public Sub AutoSumAllWorkheets()
Const MasterName As String = "Master" 'specify name of master sheet
Dim wsMaster As Worksheet
On Error Resume Next 'test if master exists
Set wsMaster = ActiveWorkbook.Worksheets(MasterName)
On Error GoTo 0
If wsMaster Is Nothing Then 'add master if not exists
Set wsMaster = ActiveWorkbook.Worksheets.Add(Before:=ActiveWorkbook.Worksheets(1))
wsMaster.Name = MasterName
'instead you can throw a message and exit here
'MsgBox "No master found"
'Exit Sub
End If
Dim FirstCell As Range, LastCell As Range
Dim ws As Worksheet
For Each ws In ActiveWorkbook.Worksheets
With ws
If .Name <> MasterName Then 'don't sum on master sheet
Set FirstCell = .Range("J3")
Set LastCell = FirstCell.End(xlDown)
LastCell.Offset(2, 0).Formula = "=SUM(" & FirstCell.Address & ":" & LastCell.Address & ")"
'write in master
With wsMaster.Cells(wsMaster.Rows.Count, "A").End(xlUp)
.Offset(1, 0).Value = ws.Name
.Offset(1, 1).Formula = "=" & LastCell.Offset(2, 0).Address(External:=True)
End With
End If
End With
Next ws
'sum all sheets up
With wsMaster.Cells(wsMaster.Rows.Count, "A").End(xlUp)
.Offset(2, 0).Value = "Total sum:"
.Offset(2, 1).Formula = "=SUM(" & wsMaster.Cells(1, "B").Address & ":" & .Offset(0, 1).Address & ")"
End With
End Sub
The first part checks if a master sheet exists and adds one if it doesn't exist.
Then I improved your code a bit:
I recommend to use clear variable names (makes it easier). For example your firstCel actually was not the first but the sum cell. That is very confusing and you will easily fail.
Use .Formula to write a formula.
I added some code to write the sums of each sheet into the master sheet. Note that this appends the entries at the master sheet. So if you run it twice you need to clear the entries in the master sheet first.
If you want to write into another column of the master sheet just change the column name of wsMaster.Cells(wsMaster.Rows.Count, "A").End(xlUp) from "A" to eg "L"

Answer 2

Try:
Sub test4()
Dim ws As Worksheet
Dim LastRowJ As Long
Dim MasterTotal As Double
For Each ws In ActiveWorkbook.Worksheets
LastRowJ = ws.Cells(ws.Rows.Count, "J").End(xlUp).Row
MasterTotal = MasterTotal + ws.Range("J" & LastRowJ).Value '<= Let us assume that total appears in each sheet at the last line in column J
Next ws
Sheet1.Range("A1").Value = MasterTotal '<= Change where you want to import the total of totals
End Sub