Most coffee table advice is about looks. Two things matter more for daily life: how the table's height compares with your sofa seat, and how much gap sits between the two. Get those right and the table feels like part of the sofa. Get them wrong and you'll be stretching for your mug or squeezing past a corner.
The usual rules of thumb, which vary a little between sources:
Height: level with the sofa seat, or up to about 5 cm lower.
Gap to the sofa: roughly 35–45 cm, enough to stretch your legs and still reach a cup.
Length: about two thirds of the sofa's width, so the table doesn't swallow the sofa or look lost in front of it.
Walkway: keep around 75–90 cm clear between the table and whatever is opposite (a TV unit, a chair, a wall), so people can pass without turning sideways.
Try it with your own room
Set the sliders to your sofa and room, then drag the table in the plan view to see how the gap and walkway change. Both views are drawn to scale.
Left: the room from above. Right: the sofa and table from the side. The green band shows the "level with the seat, up to 5 cm lower" zone. Grab the table in the left view and slide it up or down.
When to break the rules
These numbers describe a comfortable default, not a law. Break them when your room asks you to:
Small room: pull the table closer, towards 30 cm, or pick a round or oval one. Rounded edges are easier to walk past, and kinder to shins and small children.
Chunky or very low sofa: if the seat sits at 35 cm or lower, a table at the same height can look squat. Going a little higher can balance it, as long as you can still reach it from the seat.
Big sofa, big room: two smaller tables, or a table with a nesting partner, are easier to move than one long slab.
Rental or tight budget: a trunk, a pouf with a tray, a stack of sturdy crates or a second-hand side table can all do the job. If the numbers above work, anything can be a coffee table.
Before you buy anything
Measure first, and measure the right things. Stand a tape measure on the floor next to the sofa and read the height to the top of the seat cushion, not the arm or the back. Then measure the sofa's full width, and the distance from the front of the sofa to the nearest thing opposite. Put the three numbers into the planner above before you look at a single table.
It's worth marking the table's footprint on the floor with masking tape or newspaper and living with it for a day. If you trip on it or bump it, the plan is too big. Last, check the route in: doorways, the stairwell and any tight turn, especially for a long or one-piece table. Second-hand tables, tabletop trays and what you already own are all valid options before buying new.