Inserting Blank Rows in a list of existing data to "group" it

Hello All,

Very new to VBA, but am working on a project that involves several thousand lines of Excel Data. This data has to be input into another ancient system for which the input capability is 18 lines. They require that when we supply the data, it is in groups of 18 to expedite their input.

I'm trying to find a very simple formula that starts at the first row of data and will input a blank row after every 18 rows. Any assistance will be appreciated! Many of the VBA codes I have tried to use insert to the very bottom row, almost in a do-loop, regardless of if it has data or not.

The code I'm currently trying to use is

Sub insert()
m = Range("a1").CurrentRegion.Rows.Count
For i = m To 2 Step -18
Cells(i, 1).EntireRow.insert
Next
End Sub

but it isn't counting in increments of 18 as there are small groups (2 and 3 rows) of data on both the front and tail end of the data set.

Thanks!

Sub Insert_row()
With Application
.ScreenUpdating = False
.Calculation = xlCalculationManual
End With
Dim last As Integer
last = Cells(Rows.Count, 1).End(xlUp).Row
For i = 19 To last Step 19
Cells(i, 1).EntireRow.insert

Next
With Application
.ScreenUpdating = True
.Calculation = xlCalculationAutomatic
End With
End Sub

You have my thanks, worked beautifully.

yw, ty for feedback