Capacity and tank size are not the same number

The conversion, which nobody prints

There are eight pints in a US gallon. A dehumidifier rated at 50 pints a day therefore produces 6.25 gallons a day when it is working at its rated condition. Divide the tank by that and you have the interval between trips to the sink.

Read the first column carefully. In a damp basement, a 50-pint unit with a small tank is a machine you empty three times a working day. Nobody does that. What actually happens is the tank fills, the float trips, the unit shuts off, and it sits there doing nothing until somebody notices - which is often weeks.

Which is why the real answer is a hose

Tank size only matters if you are going to use the tank. Every unit in our registry except the two smallest supports continuous drainage, and in any space with a floor drain, a sump or a nearby sink below the machine, the tank should never fill at all.

That is why drainage is the first decision on this site and capacity is the second. A 50-pint machine with a 0.62 gallon tank and a hose to a floor drain is a perfectly good appliance. The same machine with no drain is a chore.

When tank size genuinely decides the purchase

• Apartments, where there is usually no drain below the machine and the bucket is the only outlet. Buy the biggest tank you are willing to carry - a full 1.7 gallon bucket is about 14 pounds. Apartment roundup.
• Pump models, as a failure fallback. If the pump quits, a large bucket holds several hours of condensate and turns a wet floor into a full tank. This is a genuine reason to prefer the Frigidaire and GE pump units over smaller-tanked rivals.
• Rooms you visit rarely. A spare room or a store cupboard where a small tank means the machine spends most of its life off.
• Upstairs rooms, where an anti-spill design matters as much as volume - a tipped bucket on a first floor is somebody's ceiling.

The specification manufacturers should publish and do not

None of these listings prints hours-to-full, which is the number an owner actually experiences. It would be trivial to compute - capacity and tank volume are both on the box - and it would make the small-tank models look considerably worse. That is presumably why nobody does it, and it is why the table above exists.