Thank you all for your explanations! Obviously my calculations had been setup too quickly ... > 13*7227*65536 / 7200 = 855162 > > The textheight is then > > 39*855162 + 10*65536 = 34006678 > > In points this is > > 34006678/65536 = 518.90073 13*7227*65536 / 7200 = 855162.88 ^^^ and then 39*855162 + 10*65536 = 34006712.32 ^^^^^^ 34006712.32 / 65536 = 518.90125 Ahhrrgg. I forgot to do integer calculations ;-( Best regards, Ulrich Dirr