Square Knot

Written by Binod Gautam

Published on:

The Square knot is one of the first knot we learn to tie.

Its a simple binding knot used to tie shoelaces, bandages and secure parcels.

The strength of this knot is only 50%, so it’s suitable for non-critical applications only.

Let’s learn this knot in detail.

History of the Square Knot

Before the name Square knot came into use, it was known as the Reef knot.

The Reef knot is one of the ancient knot and it’s history dates back to at least 4,000 years.

It was commonly used by the sailors to reef sails.

The term “Square knot” was later found in Dana’s book “A Seaman’s Friend (1841)”.

Square (Reef) Knot Details

Type: Basic

Other Names: Reef Knot, Hercules Knot

ABoK Reference: #1402

How to Tie a Square (Reef) Knot

A Popular mnemonic for tying the Reef Knot is “left over right, right over left.” 

Here are the steps:

  • square-knot-s1
  1. Cross the blue and red rope.
  2. Pass the red rope through the blue loop.
  3. Pull the ends to tighten the knot.

You have tied this knot correctly, if the working end exits both at the top or at the bottom.

diagram-of-square-knot
Square (Reef) Knot Step-by-Step

Alternate Method

  1. Form a loop on the blue rope and feed a tag end down through the loop.
  2. Bring the tag end under the bottoms and over the base of the loop.
  3. Feed it under the base of the loop.
  4. Tighten the knot.

Pro TIP: Add Extra Half Knot

Want to secure the knot?

Add an extra Half knot over the Square knot.

extra-half-knot
Image: Adding extra Half knot on top of the Square knot

You can add as many of these Half knots as you would want to give your knot additional strength.

Note that adding the half knots still does not make your knot safe for critical applications.

Square Knot Variations

square knot vs thief knot vs granny knot
Image: Reef knot vs Thief knot vs Granny knot

Surgeon’s Knot

surgeons-knot
Image : Surgeon’s knot

The Surgeon’s knot (ABoK #461) is also referred to as a surgical knot and has a slight modification to the Square Knot.

Instead of tying a single half knot in the first throw, an extra half turn is added forming a Double Overhand Knot to achieve the binding required while the second half knot is tied.

There are several variations of the Surgeon’s knot practiced by the surgeons, but the one mentioned here is the most popular and commonly used.

Granny Knot

granny-knot
Image: Granny Knot

The Granny knot (ABoK #1206) is an inferior version of the Square knot.

It’s a common error people make while tying a Square knot and they end up tying a Granny knot instead.

It consists of two identical Half Knots where one half knot is tied over the other.

But, how do you identify the Granny knot?

Simple: You will have ends exiting over and under the loop.

The knot can slip, jam and is difficult to untie than the Reef knot.

Thief Knot

thief-knot
Image: Thief Knot

The Thief knot (ABoK #1207) looks similar to the Square knot but there is one striking difference.

It does not consist of two half knots and if you look at the final structure—the tag ends emerge one at the top and the other at the bottom.

Traditionally this knot was used by sailers to determine if someone tampered with their bag or sack.

If a thief would open it, they would mistakenly tie a reef knot instead.

Tying the Shoelaces

The Square knot is the very first knot I ever learned as a child.

It’s the most basic knot used to tie shoelaces.

The Square knot for the shoestring is tied with one end and one bight, so you might not recognize it as a Square knot. 

But, it’s still there.

The Double Slip knot (ABoK #1219) can also be applied to shoestrings.

Each of the two loops in the second knot is tucked once they have been crossed.

Pros and Cons

Pros

  • Quick and easy to tie

Cons

  • Can jam
  • Can capsize if one of the free end is pulled outwards
  • Does not bind well with ropes of unequal diameter

Applications and Uses

Traditionally, the Reef knot is used by sailors for adjusting sails.

You may not remember, but this is the first knot people learn when tying the shoelaces. It’s used to tie bows in shoes and packages.

The flat nature of this knot is helpful for tying bandages over the wounds.

It is also used to secure the ends of plastic bags and when you are out camping, you can secure the rolled-up tent using a Square knot.

It is used in macrame for making decorative arts.

It’s used as a symbol in scouting uniforms and is a part of various awards and badges in Boys and Girls Scouts.

Square Knot vs Granny Knot

At first, it’s quite a challenge for beginners to spot the Square knot from the Granny knot because both knots look quite similar.

square-knot-vs-granny-knot
Image: Reef knot vs Granny knot

One way to figure them out is that in the Square knot each loop passes completely over or under the neck of the other.

The Square knot is commonly tied as “left over right, tuck under then right over left, tuck under.

The Granny knot repeats the step: “left over right, tuck under.

The Square knot has the ends leaving the loop on the same side, but the Granny knot has the ends exiting on the alternating side.

Word of Caution

The Square knot is not recommended for tying two ropes together because of the potential instability of the knot.

The Ashley Book of Knots states that:

Under no circumstances should it ever be tied as a bend….

In the same breath, he also states that:

There have probably been more lives lost as a result of using a Square knot as a bend than from the failure of any other half dozen knots combined.

The International Guild of Knot Tyers also warns:

“The reef knot should never be used as a bend to join two ropes that will be under load.”

That said, it’s fine for non-critical applications.

If you need a bend knot, there are better options like the Double Fisherman’s knot or the Sheet Bend.


I hope this article has been useful and helps you learn the Square knot quickly.

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