The manufacturers of the cord/ropes will provide reasonably accurate breaking strain forces for their cords/ropes especially where there is a safety issue.

Breaking strain forces are not the be and end all of manufacturing cords and ropes. There are elongation, dynamic loading, creep, environmental specifications as well. i.e. Mil spec Paracord being nylon has a 30% minimum elongation specification before breaking etc.

https://en.wikipedia.org/wiki/Parachute_cord

There are many types of paracord with a wide range of breaking load forces.

Dyneema cord/ropes will have a much higher breaking strain forces and improved minimum elongations etc.

Kingfisher evolution race 4mm Cord have a breaking strain of 720 Kg or 1580 lbs. i.e. 3x MIL-C-5040H 550 type III cord.

http://yachtropes.co.uk/race.php

Are you intending to do some emergency abseiling? Using paracord is probably not a good idea!

http://www.youtube.com/watch?v=OeF-Vcq2g5Y