How many 6x4 photo's can I get on an A1?

An A1 sheet measures 594 x 841 mm, while a 6x4 photo measures 152 x 102 mm. You can fit approximately 10 (5 across and 2 down) 6x4 photos on an A1 sheet, depending on the layout and any required margins. However, exact results may vary based on spacing and trimming.