How to choose a sofa: a buying guide that starts with your room

A sofa is the piece a living room is planned around, and it is usually the piece people choose last and fastest. That order is backwards. Almost every complaint about a sofa a year later comes down to one of three things: it is too big for the room, it is too deep for the people sitting on it, or the parts nobody can see were not built for daily use.

None of those are matters of taste, and all three can be settled before you order. This guide runs through the decisions in the order that actually works, from the room to the frame to the fabric. If you already know the shape you want, the sofa designs page shows what each one looks like at full size.

Start with the room, not the sofa

Take four measurements before you shortlist anything: the length of the wall the sofa will sit against, the distance from that wall to whatever faces it, the width of the walkway you need to keep clear, and the size of the window or balcony door you must not block.

Then work to two rules of thumb. Leave a walkway of at least 75 cm through the main route across the room, and keep the sofa to roughly two thirds of the length of its wall so the wall still reads as a wall rather than as a shelf for furniture. A three-seater is commonly somewhere between 180 and 210 cm long, which means a 210 cm sofa wants about 3 m of wall behind it to look settled.

Seat depth is the measurement that decides comfort

Length is what people measure. Depth is what they feel. Seat depth is the distance from the front edge of the seat to the base of the back cushion, and a difference of 5 cm changes the sofa completely.

Around 55 cm

An upright seat. Easy to get out of, kind to shorter legs and to anyone with a bad back, and the right choice for a room where the sofa doubles as the dining-side seating.

Around 60 cm

The middle ground, and the safest single answer for a family sofa where everybody is a different height.

65 cm and over

A lounging seat. Excellent for a film on a Sunday, awkward for anyone under about 5 ft 4 in, whose feet will not reach the floor without perching on the front edge.

Back angle works with it. A reclined back and a deep seat is a sofa you sink into; an upright back with a deep seat is the worst of both, because you end up sitting forward on an expensive cushion. If you can, sit on the design for five full minutes rather than five seconds. The first impression of a sofa and the fifth minute of it are often different sofas.

What is inside matters more than what is on top

Upholstery is what you choose from a photograph. The frame, the suspension and the foam are what you are actually buying. Ask about all three, in these words, and note the answers.

The frame

Solid kiln-dried hardwood is the benchmark, because kiln drying takes the moisture out before the timber is cut, so the frame does not twist as it settles. Good quality plywood in the right thickness is a legitimate choice too, particularly for straight sections. What you want to avoid is particle board anywhere structural, and joints held together only by staples. Corner blocks, dowels or screws at the joints are the sign of a frame built to be sat on hard.

The suspension

This is the layer between the frame and the cushion, and it is why two sofas with identical foam feel different. Sinuous (S-shaped) springs are the common, reliable option. Elasticated webbing is lighter and works well on low, slim designs. Eight-way hand-tied springs are the traditional top of the range and cost accordingly. Any of them is fine. Nothing at all, or thin webbing stretched too far apart, is not.

The seat foam

Foam is specified by density, in kg per cubic metre, and density is what determines whether the seat still has its shape in three years. Seat foam is commonly specified somewhere around 32 to 40 kg/m3; back cushions are softer on purpose. A soft, low-density seat feels wonderful in a showroom and develops a dip exactly where the person who always sits there sits. If a seat is described only as soft or high density with no number, ask for the number.

Choosing a shape

Shape follows the room's geometry more than it follows fashion. The table below is the short version of a decision most people take too long over.

If a corner is the obvious answer, read the sofa size guide next: it covers how to work out the two leg lengths of an L-shape and which side the return should be on. The Meridian L-shape sectional and the Halden modular sectional are the two designs worth comparing if you are weighing a fixed corner against sections you can move.

Upholstery: what each material asks of you

Every upholstery is a trade between how it looks, how it wears and how much attention it wants. Pick for the household you actually have, not the one in the catalogue photograph.

• Woven synthetics and blends. The practical default. Tight weaves resist snagging, and a mid-tone with some texture hides dust and marks far better than either a flat pale colour or a dark solid.
• Linen and cotton. Beautiful, breathable, and honest about every spill. Best in a room that is not the family's main landing spot.
• Velvet. Deeper colour than any other fabric and surprisingly hard-wearing when the pile is short and dense. It does show the direction it was last brushed in.
• Leather. The longest-lived option and the easiest to wipe clean, which is why it suits homes with children. Full grain develops a patina; corrected or bonded leather does not, and does not last as long either.
• Boucle and loop piles. Lovely texture, but loops catch on claws and rings. Avoid it if you have a cat.

Climate matters as much as the household. If you are buying in Delhi, Gurgaon, Noida or Ghaziabad, the dust and the monsoon humidity change which of these is the sensible answer. That comparison is its own article: fabric or leather in Delhi NCR's climate.

Check the access before you order

A sofa that will not go up the stairwell is a very expensive lesson. Before you confirm, measure the narrowest point on the route: the building entrance, the lift's internal depth and door width, the turn on the landing, your own doorway, and the diagonal of the door frame. Compare that to the sofa's depth and height, not its length, because that is the dimension it travels on.

If the numbers are tight, the answer is usually a knock-down design, where the legs and sometimes the arms detach, or a modular sofa that arrives in sections. Made-to-measure work has an advantage here: the piece can be built to the access you have. There is more on that trade-off in made to measure versus ready made.

The questions to ask before you pay

A seller who answers all nine plainly is a seller who knows what they are selling. If the answers get vague around the frame and the foam, that is useful information too.

The order to decide in

1. 1Measure the room, the walkway and the access route.
2. 2Fix the maximum length and depth you can live with.
3. 3Choose the shape those numbers allow.
4. 4Choose the seat depth and back angle for the people using it.
5. 5Specify the frame, suspension and foam.
6. 6Only then choose the fabric or leather.

Done in that order, the fabric decision is the fun one instead of the one that has to compensate for everything else. If you would rather talk it through than work through it alone, send the room measurements and a photo of the space: that is usually a ten-minute conversation that saves a year of regret.