Outdoor bench size guide: seating, clearances and comfort

Size is the specification people get wrong most often, and it is almost never the bench's fault. A bench that feels cramped is usually a bench that was chosen without measuring.

Here are the numbers, and then the clearances around the bench that nobody thinks about until the bench is in place.

How many people fit on a bench

The workable rule is about 24 inches (60 cm) of seat width per adult. Not 18, not 20 - those figures describe children or very friendly couples.

If the bench is for two people who will sit close, a 4-footer is fine. If it is for guests, or for people who value their personal space, go 5 or 6 feet. The difference in cost is usually small and the difference in usability is large.

Seat dimensions that decide comfort

Seat height: 17 to 18 inches (43 to 46 cm) from the ground to the top of the seat slats.

This is the number that matters most and is least often listed. Lower than about 16 inches and getting up becomes an effort, particularly for anyone with knee or hip problems. Higher than about 19 inches and your feet dangle.

If the bench will be used at a dining table, match standard chair height: 17 to 18 inches. Anything else makes the table feel wrong.

Seat depth: 18 to 20 inches (46 to 51 cm).

Depth is where comfort is won or lost. Under 17 inches and you perch. Over 21 inches and people either slouch or sit forward on the edge, which defeats the backrest entirely.

Backrest height and angle. For upright sitting, a back that reaches 20 to 24 inches above the seat at an angle of roughly 5 to 10 degrees past vertical is comfortable. Garden benches with a sculpted or curved back feel better than flat ones, and a curved back also sheds rain better.

The clearances nobody measures

This is the part that causes returns. Measure these before you buy, not after.

Behind the bench: 24 to 30 inches (60 to 76 cm) if people need to walk past it. If the bench backs onto a wall or a hedge, allow 2 inches for the backrest and anything you will lean against it.

In front of the bench: 36 to 48 inches (90 to 120 cm) of clear space. This is the leg and knee room, and it is also the path people take to sit down. A bench facing a table needs enough room to pull back and stand up without moving the table.

If it is a dining bench: measure the table's apron - the rail under the tabletop. The bench must slide under it, so the bench seat height must be lower than the apron height by an inch or more. This single measurement invalidates a lot of dining bench purchases.

Side to side: allow 6 inches beyond the bench at each end if it sits against a wall, so nobody's shoulder is against brickwork.

Weight, and why it cuts both ways

A heavy bench is stable and does not blow around, which matters on an exposed patio. It is also a problem if you want to mow under it, move it to follow the sun or store it for winter.

Decide this before buying, not after. "I'll just move it into the shed for winter" is a commitment you are making about a 40 kg bench.

Ground and levelling

Bench legs on soft ground sink, and once one leg sinks the frame twists. Twisting is what cracks joints.

• On soil or grass, put the legs on paving slabs or gravel pads.
• On decking, check the boards run under all four legs.
• On a sloped patio, use adjustable feet or pack the short legs. Do not assume the frame will flex - it will, permanently.

A short checklist

1. Measure the space: width, depth in front, walking room behind.
2. Decide how many people it really needs to seat - then add 6 inches.
3. Check the apron height if it is a dining bench.
4. Decide whether weight is a feature or a problem.
5. Check what the legs will stand on.

Get those five right and almost any bench of the right size will be comfortable. Get them wrong and no amount of wood quality fixes it. For the wood itself, see the species comparison, and for comfort once the size is right, see bench cushions.