Bistro sets look tiny in a photo and enormous the moment they arrive. The table is never the problem: it is the chairs. Every chair needs room to slide back so someone can sit down, and a balcony that looks big enough for a table can turn out too narrow for two people to actually use it.
You can find that out in ten minutes with a tape measure and no shopping at all.
Measure the floor from the wall of the house to the inside of the railing, and the length along the wall from side to side. Do it at floor level, not at the top of the railing, because planters, door frames and skirting boards eat a few centimetres. Write down where the door opens or slides, and where any drain sits, since you do not want a chair leg on top of it.
A typical balcony is somewhere around 100–160 cm deep, which is the whole story in one number. Depth decides which way the chairs can face.
Enter your balcony size, pick a table, then drag the set around. The pale zone behind each chair is the space someone needs to pull the chair out and sit. The numbers around the table show the free floor on each side, and the verdict tells you what each chair gets.
The planner uses two rules of thumb that show up in most furniture-spacing advice. Plan for at least 60 cm between the edge of the table and whatever is behind the chair, so someone can pull the chair out and sit. If you also want people to walk behind a seated guest, aim for around 90 cm. Sources differ by a few centimetres, so think of these as bands rather than hard lines.
Chairs tucked under the table need much less, which is why a folding chair that lives against the wall is a perfectly good answer on a tight balcony.
Try the two chair layouts on a balcony 140 cm deep. With the chairs on the long sides, you need roughly 60 + 70 + 60 = 190 cm of depth, so the chairs hit the railing and the house wall. With the chairs at the two ends, depth only has to hold the table itself, and the length does the rest: 60 + 70 + 60 cm along the wall is about 190 cm of length, which many balconies have.
That is why narrow balconies suit a small square or round table with the chairs at the ends, and why a table pushed into the corner is often the winning plan.
Safety guidance for balconies, for example from children's health services, says furniture, plant pots and other climbable objects should be kept away from the edge, because anything placed beside a railing can become a step up it, and light furniture can be dragged there. If children live in or visit your home, park the table and chairs away from the railing rather than flush against it.
Two other quick checks: ask your landlord or building association whether there are rules about what can go on the balcony, and avoid piling heavy planters or furniture in one spot without checking what the structure is meant to carry. If you are not sure, ask the building owner or a professional.
Measure the balcony as above, then check these before you pick a set. Compare the table size and the folded size of the chairs against your numbers, not the photo. Look for a table that is around 60–70 cm across for two people. Check whether the chairs fold or stack, because that is what lets you free the floor on a day you do not need them. Look at the material: powder-coated steel, aluminium and weather-resistant wood all work outdoors, and so does second-hand if it is sturdy. Finally, measure the door and any stairs the set has to travel through.