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What Is the Standard Size of a 3-Seater Sofa?

By Jeff Frank

The size of a 3 seat sofa usually ranges from 78″ – 90″ (198 cm – 220 cm.)

The size (length) of a sofa is determined by:

  • the width of the cushions and
  • the width of the arms.

88″ 3 seat Ashton sofa from Simplicity Sofas shown above.

Seat cushions have to be at least 21″ (53 cm) in width. This width is smaller than normal and is more commonly found on chairs rather than sofas.

  • Cushion widths of 23″ – 24″(58 – 61 cm) are the most common.
  • It is theoretically possible to have seat cushions that are 30″ (76 cm) or more, but at that point you can just add a 4th normal size cushion.
  • Seat cushions that are 27″ or wider are more commonly found only on 2 seat sofas.

Three cushions will give you a width of anywhere from 66″ – 74″ (168 – 188 cm) of space between the arms.

At that point the total width of your sofa will be determined by adding the thickness of the arms.

  • Most sofa arms are at least 3″ (8 cm) in width.
  • Most are between 4″ – 6″ (10 – 15 cm) but it is not unusual to find arms that are 8″ (20 cm) or even wider.
  • There are two arms on a sofa so you need to double the individual arm measurement.

Taking the smallest cushion width of 22″ and the smallest arm width of 3″ the smallest three seat sofa will total 72″ (183 cm).

  • In reality it will be extremely difficult to find a three seat sofa with a length of 72″ (183 cm.). Normally that sofa length comes with two cushions.

Three 27″ width cushions with 8″ arms gives a total sofa length of 97″ (246 cm.)

Theoretically it is possible to find 3 seat sofas measuring anywhere from 72″ – 97″ (183 cm – 246 cm). Though custom sofa sizes may increase the price tag.

The normal range for a 3 seat sofa, however, is 78″ – 90″ (198 cm – 220 cm.).

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4 thoughts on “What Is the Standard Size of a 3-Seater Sofa?”

  1. Good afternoon,
    I’ve purchased a very expensive sofa , which was sold as a 4 seater, yet it measures only 207cm in length. I’ve since checked other furniture stores and their 3 seater sofas measure from 207cm or more. Their 4 seaters measure from 238cm . From looking at my sofa it looks as if it could be a 3 seater as it would be impossible to seat 4 people. Are retailers allowed to sell a 207cm sofa as a 4 seater? I have contacted the retailer to ask how long are the 2 seaters and 3 seaters to match my sofa and was told the 3 seater was 200 cm and the 2 seater 165cm. Therefore, my 4 seater was just 7cm longer than a 3 seater of the same sofa. To me that doesn’t make sense.

    • I would need a brand name and model before I can answer this question precisely. In general, there are no legal restrictions on sofa sizes, but the average seat cushion is 23″ wide. Once you get down to less than 21″, the seat gets more cramped feeling. Armless chairs can be less wide and still feel comfortable.

      A 207 cm sofa is just under 82 inches. Most sofas have arms that are at least 4 inches wide. That leaves 74 inches of seating space. Dividing by 4 you get about 18 inches per seat. That is not enough to seat 4 adults.

      My guess is that your 207 cm is a typographical error or you were looking at the size of a 3 seat version of your sofa.

  2. With better quality sectionals, the arms and back are going to hold up for at least 10 years and probably 20. Other parts of the sectional, especially the cushions will fail long before that.


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