This issue plagued me for ages.

When i printed from Firefox either directly or by creating a PDF (via cutePDF), the output was scaled to about 25% of normal size making the printouts unusable.

The percetage reduction is just a guidline as there can be some variation, but the outcome is always a smaller version of what you want.

Solution

In Firefox page setup:

• remove margins
• remove shrink to fit + reset scale to 100%
• change paper type under printer options: Letter -> A4, and set to automatically select