FPDF Get page numbers at footer on Every A4 size page

To add an A4 page, with portrait orientation, do:

$pdf->AddPage("P","A4");

Create a new class which extends the FPDF class, and override the pre-defined Footer method.

Example:

class PDF extends FPDF
{
    function Footer()
    {
        // Go to 1.5 cm from bottom
        $this->SetY(-15);
        // Select Arial italic 8
        $this->SetFont('Arial','I',8);
        // Print centered page number
        $this->Cell(0,10,'Page '.$this->PageNo(),0,0,'C');
    }
}

According to my comment you can place

$pdf->PageNo();

on your page where ever you like. Also you can add a placeholder to this

$pdf->AliasNbPages(); 

What would look like

$pdf->AliasNbPages('{totalPages}');

By default it's {nb}. It's not necessary to add a placeholder

Than you could add the pagesum like

$pdf->Cell(0, 5, "Page " . $pdf->PageNo() . "/{totalPages}", 0, 1);

or without your own placeholder

$pdf->Cell(0, 5, "Page " . $pdf->PageNo() . "/{nb}", 0, 1);

this would produce e.g.

Page 1/10

in case there were 10 pages :)

But beware

Using the placeholder will mess up the width of the cell. So if you have e.g. 180 page-width than 90 isn't the mid anymore (In the line where you use the placeholder). You will see if you try :)