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How Many Modules Do You Need? A Guide to Sizing a Modular Sofa

Turn the width of your wall and the number of seats you want into a module list, using the real module widths of our Neptune, Orian, Atmosphere, Ciello, Gaia and Cassini sofas.

Updated 2 November 20269-min ReadCozey Editorial
A family relaxing on a Cozey modular sectional

Short answer: Our layouts are named by the number of seats, so start from the seat count you want in a straight row. Multiply the seat module width of your collection by that number, then add two arms if the collection uses them, or choose armless. An L-shape adds a corner module where the two legs meet, and a chaise or an ottoman adds lounging space. The result is the width you need on the wall.

Modules are the building blocks of our sofas, and each one has its own width and depth. If you know those numbers, you can check a layout against your wall before you open the configurator. Each combined width in this guide is our own sum of the listed module widths with no gap between them, so confirm the final footprint in the configurator before you order.

On This Page

  1. How do I turn a width and a seat count into a module list?
  2. What size is each module?
  3. How wide is a straight sofa with two, three or four seats?
  4. How do I plan an L-shape or sectional?
  5. Which modules should I choose, and which cannot be mixed?
  6. How much space should I leave around the sofa?
  7. Our recommendation
  8. Explore our sofas

How do I turn a width and a seat count into a module list?

Work in four steps. Our sectional sofa size guide covers how to measure the room itself, so start there if you have not yet marked out the space.

  • Step 1, set the seat count: our layouts are named by the number of seats, from 1 Seater up to 6 or 7 Seater depending on the collection, so decide how many people you want to seat in a row.
  • Step 2, multiply: take the seat module width for your collection from the table below and multiply it by the number of seats.
  • Step 3, add the arms: Neptune and Orian use two arms, and our configuration guide explains that both are required. Atmosphere, Ciello, Gaia and Cassini can be configured with two arms, one arm or no arms where the layout allows it.
  • Step 4, add the extras: a corner module for an L-shape, a chaise or an ottoman for lounging. Each one has its own size in the tables below.

Then compare the total with the wall width and the walking space you want to keep. Our guide to choosing a sofa configuration for your living room walks through that second check in more detail.

What size is each module?

These are the module sizes we list for each collection, as width by depth. Depth includes the backrest. Arms are listed separately where we publish their width.

What size is each module?

CollectionSeat moduleCorner moduleArmOttoman
NeptuneStorage seat 25.2 x 38.6 in (64 x 98 cm), or sleeper seat 39.4 x 39.0 in (100 x 99 cm)38.6 x 38.6 in (98 x 98 cm)7.1 in (18 cm) wide, 39.0 in (99 cm) deepStorage ottoman, footprint 25.2 x 20.3 in (64 x 51.5 cm)
OrianStorage or sleeper seat 30.9 x 41.0 in (78.5 x 104.2 cm)41.0 x 41.0 in (104.2 x 104.2 cm)5.5 in (14 cm) wide, 41.0 in (104.2 cm) deepStorage ottoman 30.9 x 30.9 in (78.5 x 78.5 cm)
AtmosphereRegular armless seat 29.5 x 40.6 in (75 x 103 cm); round-back version 29.5 x 38.6 in (75 x 98 cm)40.6 x 40.6 in (103 x 103 cm); round-back version 38.6 x 38.6 in (98 x 98 cm)Square arm 11.0 in (28 cm) wide, 40.6 in (103 cm) deepOttoman 29.5 x 29.5 in (75 x 75 cm); long ottoman 40.6 x 20.1 in (103 x 51 cm)
CielloRegular seat 31.1 x 37.4 in (79 x 95 cm); XL seat 35.0 x 40.2 in (89 x 102 cm)Regular: see the configurator; XL 40.2 x 40.2 in (102 x 102 cm)See the configuratorRegular ottoman 31.1 x 31.1 in (79 x 79 cm); XL ottoman 35.0 x 35.0 in (89 x 89 cm)
GaiaRegular armless module 33.1 x 34.8 in (84 x 88.5 cm); XL 35.8 x 37.4 in (91 x 95 cm), measured with coversRegular 33.9 x 33.9 in (86 x 86 cm); XL 36.6 x 36.6 in (93 x 93 cm)See the configuratorRegular storage ottoman 33.1 x 33.1 in (84 x 84 cm)
CassiniArmless seat 26.4 x 36.0 in (67 x 91.5 cm)36.0 x 36.0 in (91.5 x 91.5 cm); the wedge seat is 30.3 in (77 cm) wideLeft and right arm modules; see the configuratorNo matching ottoman in our current Cassini layouts

Our sofa seat depth and height guide explains how the seat depth feels in each collection. The Ciello chaise is 54.5 inches (139 cm) deep, and our configuration guide gives 68.5 inches (174 cm) for the overall depth of a Regular two-seater with a chaise. The Gaia chaise is 55.1 inches (140 cm) deep in Regular and 59 inches (150 cm) in XL. Atmosphere sizes above are for Regular seats; Storage and Sleeper modules can differ, so read those in the configurator.

How wide is a straight sofa with two, three or four seats?

For the collections where we publish the arm width, you can add it up yourself. Each figure below is the sum of the listed module widths, with no gap between modules. The Neptune and Orian rows include two arms, and the Cassini and Atmosphere armless rows include none.

How wide is a straight sofa with two, three or four seats?

Layout2 seats3 seats4 seats
Neptune, storage seats with two arms64.6 in (164 cm)89.8 in (228 cm)115.0 in (292 cm)
Orian, two arms72.8 in (185 cm)103.7 in (263.5 cm)134.6 in (342 cm)
Atmosphere Regular, armless59.1 in (150 cm)88.6 in (225 cm)118.1 in (300 cm)
Atmosphere Regular, two high arms81.1 in (206 cm)110.6 in (281 cm)140.2 in (356 cm)
Cassini, armless52.8 in (134 cm)79.1 in (201 cm)105.5 in (268 cm)

Our configuration guide confirms the two-seater widths of about 53 inches for armless Cassini, 59 inches for armless Atmosphere, 64.6 inches for Neptune with arms, 72.75 inches for Orian with arms and 81.1 inches for Atmosphere with high arms, plus 89.8 inches for the Neptune three-seater. The other three- and four-seat totals extend the same sums and are not published as separate figures. For Cassini with arms, that guide lists the two-seater at about 72 inches. For Ciello and Gaia, read the complete assembled width in the configurator, because the module sizes above are measured with cushions and covers.

Sleeper seats are wider than storage seats in Neptune, so a Neptune layout with a sleeper seat is wider than the figures above. Read that total in the configurator too.

How do I plan an L-shape or sectional?

An L-shape adds a corner module where the two legs meet. The corner is counted once, so the width of each leg is the seat modules on that leg plus the corner module.

For example, an armless Cassini with one seat, a corner and one seat is 26.4 inches (67 cm) of seat plus a 36.0 inch (91.5 cm) corner on each leg. That adds up to 62.4 inches (158.5 cm) by 62.4 inches (158.5 cm), which matches the roughly 62.5 inches in our configuration guide. For the other collections, read the L-shape footprint in the configurator, because module sizes and assembled sizes are not the same.

Our configurator names the larger shapes by seater count and layout, for example 3 Seater with Corner L, 5 Seater with Corner R and 6 Seater "U" for Neptune, Orian, Atmosphere, Ciello and Gaia, and Left, Right, Corner, Wedge and "U" versions for Cassini. Pick the layout that matches your room, then read the footprint on the product page. Our compact sectionals guide lists smaller L-shapes for tight rooms.

Which modules should I choose, and which cannot be mixed?

Some choices are fixed once you start, and it helps to know them before you count modules.

  • Ciello and Gaia: Regular and XL seating modules cannot be mixed in one sectional.
  • Ciello backrests: use either Original or High Angled across the sofa.
  • Atmosphere: Regular, Storage and Sleeper seats cannot be combined in one sofa, and changing from one to another needs a new sofa.
  • Neptune and Orian: both arms are required, and left and right arms are specific to their side.
  • Cassini: moving an arm to the other side needs the matching left or right arm module.

These rules come from our modular sofa guide and our configuration guide, so check them against the configurator for your exact layout.

How much space should I leave around the sofa?

Once you have a total width and depth, compare it with the room. Our configuration guide uses about 30 inches (76 cm) of walking space as a planning target, with 24 inches (61 cm) possible in a tight home and 36 inches (91 cm) more generous. That is general advice, not a product specification, so measure the clear route in your own room.

Include the chaise, the ottoman and any open sleeper surface in your footprint. For rooms with limited floor area, our guide to sofas for small apartments and condos compares sizes by actual width.

Our recommendation

Start with the wall, then work backward to the module list.

  • A short wall, around 53 to 65 inches (135 to 165 cm): a two-seat layout, such as an armless Cassini at 52.8 inches (134 cm) or a Neptune with two arms at 64.6 inches (164 cm).
  • A standard three-seat sofa: three seats in a row. Adding the module widths gives 79.1 inches (201 cm) in armless Cassini, 88.6 inches (225 cm) in armless Atmosphere or 89.8 inches (228 cm) in Neptune with two arms.
  • A long wall of 100 inches (254 cm) or more: an armless Cassini four-seater at 105.5 inches (268 cm), or an Orian three-seater with arms at 103.7 inches (263.5 cm).
  • A corner or open-plan room: an L-shape with one corner module, adding seat modules to each leg.
  • A room where you want to stretch out: add a chaise or an ottoman where your collection offers one, such as the Ciello or Gaia chaise, or an ottoman for Neptune, Orian, Atmosphere, Ciello or Gaia.

Explore our sofas

Product specifications can change. Check the current dimensions on the product page before ordering.

Frequently Asked Questions

For a straight sofa, choose the 3 Seater layout, which is three seats in a row, plus two arms if the collection uses them. In Neptune and Orian the two arms are required, and in Atmosphere, Ciello, Gaia and Cassini you can choose two arms, one arm or none. Summing three listed seat modules with no gap, plus arms where they apply, gives 79.1 inches (201 cm) for three armless Cassini seats, 88.6 inches (225 cm) for three armless Atmosphere seats and 89.8 inches (228 cm) for three Neptune storage seats with two arms. Our configuration guide confirms the Neptune figure. Confirm the final width in the configurator.


Measure the wall and the floor depth first, then decide how much walking space to keep. Divide the usable wall width by the seat module width for your collection to see how many seats fit, and subtract the arms where they apply. A Neptune two-seater with arms is 64.6 inches (164 cm) and an armless Cassini two-seater is 52.8 inches (134 cm), for example. Choose the matching layout in the configurator and compare its footprint with your marked-out space. If the numbers are close, try a layout with fewer seats or no arms.


Place the longest run of seat modules along the longest clear wall, and keep the walking route open on the other sides. Use a corner module only where the room has a natural corner to fill, because it turns the sofa into an L with two legs. Add an ottoman or chaise last, since each one extends the footprint toward the room. Our configuration guide suggests about 30 inches (76 cm) of walking space as a planning target. Tape the outline on the floor and walk around it before you order.


Match the legs of the L to the two walls that meet in the corner. Add up the seat modules on each leg and the corner module once: an armless Cassini with one seat, a corner and one seat comes to 62.4 inches (158.5 cm) on each leg. In a narrow room, keep the long leg against the longer wall and the short leg against the shorter one, then check that doors and walkways stay clear. In an open-plan room, consider the U-shaped layouts, such as 6 Seater "U". Read the exact footprint in the configurator.


Yes, within the limits of your collection. Our modular sofas are designed so that you can add modules as your space or household changes, and our sectional size guide notes that you are not committing to a permanent size at purchase. The limits matter: Regular and XL Ciello or Gaia modules cannot be mixed, and Atmosphere Regular, Storage and Sleeper seats cannot be combined. Neptune and Orian arms are side-specific. Check that any module you want to add is compatible with your sofa before you order it.


Arms add width but they are not seat modules, so they do not change how many seats you have. In Neptune, each arm is 7.1 inches (18 cm) wide, and in Orian each arm is 5.5 inches (14 cm) wide, so two arms add 14.2 inches (36 cm) or 11.0 inches (28 cm). In Atmosphere, each square arm is 11.0 inches (28 cm) wide. Removing arms from Atmosphere, Ciello, Gaia or Cassini saves width, but it also removes a place to lean, so choose based on your wall and how you sit.

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