550 parracord for climbing?

[Scythe13]

Paracord will kill you! Stay well away from it as a climbing rope.

Yes it is strong. Yes it can take your weight. Yes it is pretty light.

Now the negatives.
It's very narrow, so will rip your hands to shreds.
It's not very heat resistant, so the heat from the friction will destroy it.
It's not very friction resistant, so general wear and tear will destroy it.
There is not a lot of 'give' in the rope, so it would REALLY aggressively stop you, if you fell.
Back to the narrow bit, if you fell, it would cut into you (huge pressure, small surface are to take the impact of the rope against your body).
Belay devices are made for larger thicknesses of rope, so you'll not be getting the 'lock off' benefits if you get tired and need to take a break...your climbing partner will not be able to lock off very easily, if at all.
The surface is SUPER abrasive, so if you did fall, the friction would rip through the hand of whoever is belaying for you.

All the above applied for both climbing and rappelling. A figure 8 would just melt the 550 cord.

A good climbing rope, for a small enough distance, e.g. 30 or 40 meters, will probably only cost around the £40 mark. To put your life in the hands of a £3.50 length of shoelace, or a specialised piece of equipment....for me it's an easy call.