Our verdict
Pick the Dreo HM311 if you want the lower price. Pick the Dreo HM311S if it is the cheaper of the two on the day you buy.
The central trade-off
Tank size. Dreo HM311 Humidifier: 4 liters; Dreo HM311S Humidifier: 4 liters.
Rated area. Dreo HM311 Humidifier: 300 square feet; Dreo HM311S Humidifier: 300 square feet.
Power draw. Dreo HM311 Humidifier: 26 watt-hours; Dreo HM311S Humidifier: 26 watts.
Price. When we checked, the Dreo HM311 Humidifier listed for less ($36 against $45); prices move, so check both buttons.
Side by side
| Specification | Dreo HM311 Humidifier | Dreo HM311S Humidifier |
|---|---|---|
| Type | Not stated by the maker | Not stated by the maker |
| Tank | 4 liters | 4 liters |
| Run time per tank | Not stated by the maker | 36 hours |
| Rated area | 300 square feet | 300 square feet |
| Noise | Not stated by the maker | 28 dB |
| Power draw | 26 watt-hours | 26 watts |
| Model number | DR-HHM001 | DR-HHM001S White |
Values are the makers' published specifications. "Not stated" means the maker doesn't publish it.