Men's blazers, suits and sports jackets — when to wear them and what styles work?

They are the foundation of every good wardrobe and knowing how to switch between them will see wearers through most occasions

A cream suit for men, designed by Kim Jones for Dior Homme. EPA

Knowing the difference between a suit jacket, a sports jacket and a blazer, and when to wear each of the styles, seems to be an enduring fashion challenge for men.

In truth, there is not a huge amount to separate them unlike, say, a tracksuit and a tuxedo. The differences are subtle at best but important. While one will see you through most formal occasions, another will add a snap to otherwise casual jeans.

Today, there is often little to tell the three apart, so knowing which one to wear, and when, will keep you one step ahead of the crowd.

Suit jacket

A suit jacket is, as the name suggests, the jacket component of a two or three-piece suit. By definition, it is made in the same material as the trousers. It is relatively formal but can vary from being loose cut and double-breasted, as seen at the recent Dior spring/summer showcase, or to highly structured and slim-fitting, as shown at Saint Laurent.

A suit jacket has two or three buttons with a flat, notched collar. Irrespective of the fit, it will always be tailored in some way, even the unlined, linen suits from Italy that are a master class in construction. With no lining to hold it all together, the jacket must be cut to perfection to retain its shape.

While there are no rules to say that a suit jacket cannot be worn with different trousers, such as jeans, this could mean that the jacket will wear out differently from the trousers. Given that suits are expensive, it is worth looking after both pieces properly.

A standard office suit is usually made of lightweight wool that is effective at keeping the wearer warm in winter and cool in summer. While this will suffice for lots of occasions including weddings, a good rule of thumb is that the more formal the occasion, the darker the suit colour should be. One would never, for example, wear a pale seersucker suit to a funeral, unless specifically requested by the dearly departed.

The suit is to men what the LBD is for women — a go-to failsafe that can be worn to an array of events. Switch up the shoes and the tie and you are good to go.

Blazer

A blazer is a stand-alone item in its own right and will always be a more relaxed alternative to a suit jacket. It is not designed to be worn as a matching look, so the fun lies in what and how to mix it up. Take Dolce & Gabbana for example, who recently offered a lavishly embellished blazer worn with distressed jeans to make it more casual.

With its roots in the British Army in the early 19th century, when it was a rather formal double breast with six buttons, , the blazer was later adopted by rowing clubs, which reduced it to a two-button, single breast with added bright colours and stripes. A good rule for wearing a blazer with panache is mixing it with its opposite. While Dolce & Gabbana mixed embroidery with ripped denim, cargo pants and trainers also look amazing with a blazer in a sombre tone.

Sports jacket

A heavier variation on the blazer, the sports jacket comes from very different roots. For years, men would wear what was called a morning jacket — namely a tailored, hip-length jacket worn with non-matching trousers. This was the set outfit for shooting, a pastime of the landed gentry, and in time evolved to become the Norfolk jacket, a sturdy, yet tailored jacket in heavy tweed or worsted wool that came with a belt.

Both practical and very stylish, this natty, outdoorsy jacket with its overtones of old money was also adopted by men from all walks of life. It soon lost the belt but has retained some of the original elements, including suede patches to reinforce the elbows, and pleats at the back for easy movement.

Most are usually found in herringbone, tweed and flannel, and sometimes, but not always, come with a patch pocket on the breast.

The sports jacket is the most laid-back of the three, and today has largely lost its connection to outdoors.. At its spring/summer showcase, Thom Browne went for a very playful take, layering multiple sports jackets on top of one another, clashing the ice cream shades of tweed. Loose and boxy, and worn with trousers shorn at the ankle, it was the welcome update the sports jacket has been waiting for.