The half-Windsor knot, also known as the single Windsor knot, is a way of tying a necktie

Necktie

A necktie is a long piece of cloth worn for decorative purposes around the neck or shoulders, resting under the shirt collar and knotted at the throat. Variants include the ascot tie, bow tie, bolo tie, and the clip-on tie. The modern necktie, ascot, and bow tie are descended from the cravat. Neck...

 which produces a neat, triangular knot. It is larger than the four-in-hand knot

Four-in-hand knot

The four-in-hand knot is a method of tying a necktie. Also known as a simple knot or schoolboy knot, the four-in-hand is believed to be the most popular method of tying ties due to its simplicity...

 and Pratt knot

Pratt knot

The Pratt knot is a method of tying a tie around one's neck and collar. It is also known as the Shelby knot and the Pratt-Shelby.The knot was invented by Jerry Pratt, an employee of the US Chamber of Commerce. He had been wearing his tie in the Pratt knot for some twenty years before it became...

 but smaller than the Windsor knot

Windsor knot

The Windsor knot, also referred to as a Full Windsor or as a Double Windsor to distinguish it from the half-Windsor, is a method of tying a necktie around one's neck and collar. The Windsor knot, compared to other methods, produces a wide symmetrical triangular knot. The knot is often thought to...

. The half-Windsor is derived from the full Windsor in that it is only brought up around the loop on one side rather than both. It works well with light- and medium-weight fabrics.

Tying

To tie the half-Windsor, place the tie around your neck and cross the broad end of the tie in front of the narrow end. Fold the broad end behind the narrow end and bring it forward on the opposite side. The left and right sides of the narrow end, and the inside of the loop around your neck, form a triangle. Continue folding the tie over the sides of this triangle, rotating around the triangle in one direction. The sixth fold should bring the broad end up over the top of the knot from behind; push the end down through the loop in front of the knot between the fourth and fifth folds, work out any wrinkles, and pull the knot tight. If the tie is unbalanced, untie the knot and try again giving yourself more or less length to work with. The steps are: Start with the wide end of the tie on your right and extending a foot before the narrow end, Cross wide end over narrow and turn back underneath, Bring it up and turn it down through the loop, Pass the wide in from the front, from the left and to the right, Then, end up through the loop, and put it down through the knot in the front, tighten the knot carefully and draw it up to the collar.

According to The 85 Ways to Tie a Tie

The 85 Ways to Tie a Tie

The 85 Ways to Tie a Tie is a book by Thomas Fink and Yong Mao. The authors were research fellows at Cambridge University’s Cavendish Laboratory...

 (Thomas Fink

Thomas Fink

Thomas Fink is an Anglo-American physicist who has authored a number of journal articles on statistical and biological physics and two popular books. He is a Chargé de Recherche at CNRS/Institut Curie and when not in Paris lives in London....

 and Yong Mao), the knot is tied

• Li Ro Ci Lo Ri Co T (knot 7)

with a common variation being

• Li Ro Ci Ro Li Co T (knot 8).

The former is not self-releasing, while the latter is.

See also

• Windsor knot
  Windsor knot
  The Windsor knot, also referred to as a Full Windsor or as a Double Windsor to distinguish it from the half-Windsor, is a method of tying a necktie around one's neck and collar. The Windsor knot, compared to other methods, produces a wide symmetrical triangular knot. The knot is often thought to...
  
   – a substantially bulkier knot
• Four-in-hand knot
  Four-in-hand knot
  The four-in-hand knot is a method of tying a necktie. Also known as a simple knot or schoolboy knot, the four-in-hand is believed to be the most popular method of tying ties due to its simplicity...
  
  
• List of knots