By default OS X sets US letter as the 'Default paper size' under System Preferences -> print & scan. This can cause printing issues when trying to print to a thermal receipt printer such as the Star tsp100.

Please note there appears to be a bug in older versions of OSX (Leopard 10.6 and below) which prevents users from performing step 2 below. So while you can set a custom print size, Mac OSX 10.6 will not let you set a custom default print size. OSX 10.7 (Lion) work fine, and upgrading to this version will fix this issue.

How to set the default paper size

Step 1

1. In Google Chrome press Command + P

2. Click the drop down 'Paper Size' then select 'Manage custom sizes'

3. Click the + sign to create a new paper size, you can change the name by double clicking on 'untitled'

4. Please ensure the following settings settings.

   • Click OK to return to the print dialogue box

   • Click Cancel

   Step 2

   1. Navigate to System preferences

   2. Set your thermal receipt printer as your default printer

   3. Set the paper size to the template you just created