There are several standard sizes of French posters although the measurements can vary depending on studio and year.  Although there are other sizes as well, the standard sizes are as follows:

• French 1p - known as a "Grande" poster and measure approximately 47" x 63" or 120cm x 160cm
  This is the standard French poster size
   
• French 2p - known as a "Double Grande" poster and measure approximately 63" x 94" or 160cm x 240cm
  These are printed in two pieces that overlap to form this large poster size.  They are normally horizontal format posters, but can also be vertical.
   
• French 23x32 - known as an "Affiche" poster and measure approximately 23" x 32" or 60cm x 80cm
   
• French 15x21 - known as a "Petite" poster and measure approximately 15" x 21" or 40cm x 60cm
   
• French LCs - measure approximately 8 1/2" x 11" or 21cm x 27cm.  These are usually issued as sets of 8, but may also be issued as a set of 6, 10, or 12.  For some films, up to three different sets may be issued which are designated with "A", "B", and "C".
   
• French door-panel - known as a "Pantalon" poster and measure approximately 23" x 63" or 60cm x 160cm
   
• French 31x47 - measure approximately 31" x 47" or 80cm x 120cm
  If you know the official French poster name for this size, please tell us.
   
• French 4p - known as a billboard poster (we don't know the official French name) and measure approximately 91" x 123" or 240cm x 320cm
  These are printed in four pieces that overlap to form this large poster size.
  If you know the official French poster name for this size, please tell us.
   
• French 8p - known as a billboard poster (we don't know the official French name) and measure approximately 118" x 156 3/4" or 300cm x 400cm
  These are printed in eight pieces that overlap to form this large poster size.
  If you know the official French poster name for this size, please tell us.