Bathroom trash can sizes

One to two gallons (4-7.5 liters) for an en-suite or guest bathroom, two to four gallons (7.5-15 liters) for a shared family bathroom, and four to eight gallons only if it takes diapers. The limiting dimension is almost always width, not volume.

That last point is what makes bathroom sizing different from kitchen sizing. In a kitchen you are choosing a capacity. In a bathroom you are filling a gap — between the toilet and the wall, beside a vanity, behind a door — and that gap is often six or seven inches wide. Volume is almost never the constraint.

The Umbra figure is worth singling out because it shows what is achievable: a genuine two-gallon bin that is 6.5 inches wide. Most two-gallon bins are round and roughly ten inches across, which wastes most of a rectangular gap. If your slot is narrow, a rectangular bin is not a preference, it is the only thing that works.

Kitchen cans converged on 13 gallons because the bag market converged on 13 gallons. Nothing similar happened at the small end: there is no dominant bathroom bin size, so manufacturers pick whatever suits their mold and label it in whichever unit flatters it.

The practical consequence is that you will see the same bin listed as 2 gallons on one retailer, 7.5 liters on another and 8 quarts on a third, and none of them is wrong. Convert everything to one unit before comparing: multiply gallons by 3.785 for liters, or by four for quarts. The full conversion chart.

It also means the gallon figure tells you almost nothing about whether a bin fits your gap. Measure the gap, get the bin's actual width and depth, and ignore the capacity unless it is obviously wrong for the room.

This is where small bins get annoying, because the bag ladder has even less structure down here than it does in the middle.

The last row is not a joke either. For a bathroom bin taking dry waste — tissues, cotton pads, packaging — a reused grocery bag works, costs nothing and is usually closer to the right size than a purpose-bought liner. The case for a proper liner is a bin that takes anything damp, where you want a seal and a bag that will not tear when you lift it.

Small bins have the same fit problem as big ones, incidentally: the liner is cut oversized and slides down as it fills. Same causes, same fixes.

Lid or no lid. It is the only real decision in bathroom bins and it comes down to three questions.

• Does anything damp or smelly go in it? If yes, you want a lid. If it is tissues and packaging, an open bin is easier to empty and far easier to clean.
• Is there a dog or a toddler in the house? Then a lid, and ideally a heavy or latching one. A bathroom bin is the most raided bin in most homes.
• Does the bathroom share a wall with a bedroom? Then a damped lid rather than a sprung flap, which snaps shut loudly and eventually stops latching. Our bathroom picks.

Beyond that, the thing that will actually determine whether you like the bin is how easily it cleans. Bathroom bins get wet inside and out; smooth interiors, rounded internal corners and no seam at the base are worth more than any other feature at this size.