Main Parts of a Sofa and Couch (2 Diagrams For Internal and External Parts)

There’s more to a sofa and couch than meets the eye, and the construction of a sofa will play a large part in how comfortable it is and what price point it sits at. Here we uncover the many parts of a sofa to offer a better understanding of this much-loved piece of lounge furniture.

We also include two amazing custom diagrams that identify the major internal and external parts of a sofa and couch

External Parts of a Sofa and Couch

External Parts of a Sofa and Couch Diagram
External Parts of a Sofa and Couch Diagram

Sofa & Couch Back

The back of the sofa is made up of two further parts; the inside back and the outside back. The inside back is that part that will come into contact with a person sitting on the sofa, while the outside back might be against a wall.

The inside back is smaller than the outside back, as it goes from the top of a sofa to the seat cushions, whereas the outside back comprises the whole back upholstered area of the sofa, from the top to the base. The inside back can be made of various components depending on the type and style of the sofa.

Some types of sofa backs include:

Tight Back: On this type of sofa, the inside back will have upholstery covering a firm filling and no fitted cushions. This type of sofa has a formal style and looks clean and minimalist.

Pillow Back: This type of sofa will have an inside backfilled with moveable cushions. This makes for a very comfy sofa with a more casual feel.

Attached Back: The inside back of this type of sofa has cushions that are fixed in place. They could be zipped, stitched, or stuck to the sofa with velcro. This is a low-maintenance style of sofa and is very common.

Sofa & Couch Arms

The arms of a sofa are the end parts that are situated higher up on the sofa than the seats but generally not as high up as the top of the backrest. The arms of the sofa work as armrests for the person sitting on the sofa, and they also create an enclosed shape to stop anyone from falling off the end and a corner space to snuggle up in.

The arms of the sofa are made up of the inside arms and the outside arms. The inside arms are on the inner portion of the sofa, where they meet up with the seat cushions. As they form a part of the sofa where a person will be resting, they are often padded or cushioned. The outside arms are the outer ends of the sofa ranging from the sofa base up to the point where the arm becomes the armrest.

There are many different types of sofa arms depending on the style of the sofa, some of which are:

Rolled Arm: This is a popular shape of a sofa arm with a heavily curved shape. It makes for a very comfortable space to lounge, but the drawback of these types of sofa arms is that they take up a lot of space and can look old-fashioned.

Box Arm: Also known as a square arm, this type of sofa arm is angular and box-shaped. It is handy when entertaining as the arms of the sofa serve as an extra surface where guests can place their drinks or as an additional seat for someone to perch on. However, they can be uncomfortable for lounging on and will require throw cushions.

English Arm: This sofa arm is set back from the sofa seat edge and has a more slender shape, ideal for small spaces or cleaner lines.

Seat & Couch Cushions

The seat cushions on a sofa are the large padded cushions that are positioned on top of the seat frame. These cushions can be permanently attached to the sofa via stitching, or they can be removable, which makes for easy cleaning.

This also means you could turn the seat cushion over if you end up with a stain you are unable to remove. Seat cushions will be filled with different types of padding, and this is a key component when it comes to comfort and price.

Sofa & Couch Skirt

Some sofas will have a sofa skirt, which is like a fabric valance surrounding the base of the sofa. A sofa skirt gives a sofa a more traditional look and hides the floor underneath the sofa so that the sofa appears to reach the floor. A sofa skirt will be made up of different components, including a front skirt, side skirts, and corner skirt panels which are usually pleated.

Sofa & Couch Legs

Sofa legs can be an internal or external part of the sofa, depending on the design. Modern sofas have visible legs, which can be an essential part of the style as well as the construction. They could be made from solid wood, wood veneer, metal, or plastic and be of various shapes and sizes. The legs of the sofa are also key to its stability.


This external part of a sofa refers to the fabric which covers the majority of the furniture. Leather or faux leather fabrics are popular on sofas as they are easy to wipe clean, whereas cotton, linen, or microfiber fabrics tend to be more snuggly and comfortable. Velvet sofas are also a popular choice for many interior styles.

Internal Parts of a Sofa & Couch

Internal Parts of a Sofa and Couch Diagram
Internal Parts of a Sofa and Couch Diagram

Sofa & Couch Frame

The sofa frame forms the skeleton of this piece of furniture. Solid wood frames will result in more sturdy, long-lasting sofas, but many modern sofas have frames made from fiberboard to keep costs low.


Many sofas have springs beneath the sofa seat area, which provide support and allow the seat to have a slight bounce. The springs will be made from metal.

Padding and Stuffing

Most sofas will have several types of padding or stuffing. Often, the seat of a sofa will contain multiple layers of padding, much like a mattress.

This will usually include various types of foam, such as high-density foam and memory foam. Some parts of the sofa might also contain internal padding and stuffing in the form of polyester fibers or down feathers.

Here is a diagram that illustrates all internal and external parts of a sofa and couch.

Parts of a Sofa and Couch Diagram
Parts of a Sofa and Couch Diagram