Slipped overhand knot (slip knot)

The knot is a perfectly ordinary overhand, except that a small bight instead of the end is pushed through the loop. The actual end stays outside. As long as nobody pulls the end, the knot holds like an overhand: the loop nips the bight.

When you pull the tail, the bight gets shorter until it slips through the loop. Then there is nothing left for the loop to hold, and the knot opens completely. 'Slipping' a knot is a general principle: many knots can be finished this way and so become quick-release.

It matters which strand forms the bight. If it is formed from the working end, you get the slipped knot, which releases with a pull on the end. If it is formed from the standing part, you get a running noose that tightens under load. Both are often casually called a 'slip knot' – so it pays to look closely.

A correctly tied slipped overhand shows a small bight sticking out of the knot, and beside it the tail belonging to that bight. The standing part runs into the knot without a loop. Do the test: a gentle pull on the tail must open the knot. If instead a loop tightens around something, you have tied a running noose.

Dress the knot before setting it, and pull on the bight and standing part. Make sure the tail isn't too short – after all, you need it to release the knot – and that it can't snag anywhere it might be pulled by accident.

A running noose must never be put around the neck or limbs of people or animals – not in play, not even 'just for a moment'. It tightens under load and does not let go by itself. Explain this to children who play with rope, too.

The second danger is accidental release. If the tail hangs free, it can catch on a branch, a bag or clothing and open the knot. So use the slipped knot only for light, non-critical purposes. None of the knots in this atlas is meant for life-safety use – not for climbing, abseiling, rescue or holding and lifting people. Life-safety use only after proper training with certified equipment.

The knot shows its strength where something is opened and closed often: closing a sack or bag, setting a temporary stopper, tidying lines you'll need again soon. It saves time and fingers because no tightly set knot has to be picked apart.

It is unsuitable for anything that must not release by accident, and for places where the tail can snag or be pulled. For a secure attachment, use a different knot.

Form a loop as for an overhand knot. Fold the end into a small bight and push only that bight through the loop. Set it by pulling the bight and standing part, then release it with a pull on the end. Repeat a few times.

Then deliberately tie the other form, with the bight taken from the standing part, around a stick (never a body part) and watch it tighten. Once you can reliably tell the two apart, you understand the principle of slipping – and can apply it to other knots later.