Why use pdfs for archiving engineering calculations?

Four reasons for a start:

• You can print a copy from almost any format. Even Linux and Apple users get the same printout
• It is likely you will still be able to print a copy 15 years from now.
• PDF is the most widely used format with lots of free open source tools as well as the original Adobe ones.
• You can easily store most common types of documents - drawings, reports and scanned documents in pdf. 

Spreadsheets change over time – almost mysteriously. Print a calculation spreadsheet a year after you last used it and it has nearly always changed. Links are missing, dates have changed, someone has updated it. So save a pdf snapshot of important spreadsheet calculations. This is part of a bigger discussion about electronic engineering files, preserving records and doing calculations in the modern world.

It is always wise to produce a .pdf copy of any report including all attachments and figures. That way, a year from now you can find exactly what you sent and carry an electronic copy with you everywhere. This should go without saying – but I'm surprised how often it doesn’t.

Oh and by the way pdfs can easily be edited (unless they are locked) so don’t assume that they are unchanged from the original.