How to only allow negative numbers in Excel?

In Excel, how to only allow negative numbers entered? This article will introduce some useful and quick tricks for you to solve this task.

Only allow negative numbers in Excel with Data Validation

Only allow negative numbers in Excel with VBA code

Only allow negative numbers in Excel with Data Validation

Normally, the Data Validation function can help you, please do as follows:

1. Select the cells or column that you want to allow only negative numbers entered, and then click Data > Data Validation > Data Validation, see screenshot:

2. In the Data Validation dialog box, under the Settings tab, do the following options:

(1.) In the Allow section, choose Decimal from the drop down list;

(2.) In the Data section, please choose less than or equal to option;

(3.) At last, enter the number 0 into the Maximum text box.

3. Then click OK, and now, only negative numbers and 0 are allowed to be entered, if positive number entered, it will display a warning message, see screenshot:

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Only allow negative numbers in Excel with VBA code

Here is a VBA code also can help you, with the following code, when you enter a positive number, it will be converted to negative automatically, please do as follows:

1. Right click the sheet tab that you want to allow only negative numbers, and choose View Code from the context menu, in the popped out Microsoft Visual Basic for Applications window, please copy and paste the following code into the blank Module:

VBA code: Only allow negative numbers in worksheet:

Private Sub Worksheet_Change(ByVal Target As Range)
'Updateby Extendoffice
    Const sRg As String = "A1:A1000"
    Dim xRg As Range
    On Error GoTo err_exit:
    Application.EnableEvents = False
    If Not Intersect(Target, Range(sRg)) Is Nothing Then
        For Each xRg In Target
            If Left(xRg.Value, 1) <> "-" Then
                xRg.Value = xRg.Value * -1
            End If
        Next xRg
    End If
err_exit:
    Application.EnableEvents = True
End Sub

Note: In the above code, A1:A1000 is the cells that you want to only input negative numbers input.

2. Then save and close this code, go back the worksheet, and now, when you enter some positive numbers into the cells you specified in the code, the positive numbers will be converted to negative ones automatically.