Help image prints out smaller than print size

[Lenswork]

I just know this is going to be a stupid question buuuuut.
I processed an image in elements 6. Resized it to 80mm x 48mm, roughly credit card size, 100ppi. this was done on my laptop. I then load it onto a stick so i can print it from my pc, load 6x4 paper into the printer and print. But the image comes out at 50mmx38mm! Any ideas where i'm going wrong? OP on both systems is XP pro. No elements on PC the image opens in paint before printing.
Thanks in advance

 

[arad85]

Sounds like the output printer is running at 160ppi. The way to do this is work backwards from the printer. Find it's resolution in ppi and then make the image with those ppi values. Personally, I always work in pixels rather than measurements and ppi - more direct and, IMHO, easier to understand.

 

[Lenswork]

Sounds like the output printer is running at 160ppi. The way to do this is work backwards from the printer. Find it's resolution in ppi and then make the image with those ppi values. Personally, I always work in pixels rather than measurements and ppi - more direct and, IMHO, easier to understand.

Thanks for the reply arad85. It makes sense what you say. I'll try to put it into practise later.
Thanks again

had to go into printing preferences>user defined to sort it out.
Thanks for replying arad85.