Humidifier Size Calculator
Enter the room area, ceiling height and whether the room leaks air - old windows breathe a lot, new builds barely. The calculator gives the gallons-per-day output to shop for, the tank class on the shelf, and how many refills a day that really means.
Box ratings assume a sealed room with the windows shut. This one prices reality: leaky rooms need a third more capacity, ultrasonic units dust everything with minerals unless you run distilled, and past 40 percent humidity the windows start sweating - the built-in humidistat beats any timer.
How to use
- Measure the room the humidifier will actually live in, not the whole floor.
- Be honest about the leakiness - drafty sash windows change the answer.
- Shop the tank class, then check the refill width: one gallon a day is a jug a day.
Frequently asked questions
What size humidifier do I need for my room?
Roughly 1 gallon per day for 300 square feet, scaling with ceiling height and air leaks. A leaky 400-square-foot bedroom can need double the rating of a tight one - the calculator prices the leaks instead of ignoring them.
What humidity should my house be in winter?
30 to 40 percent. Below that, static shocks and dry throats; above it, condensation on the windows and mold risk in the corners. That ceiling is why the humidistat matters more than the run time.
Why does my ultrasonic humidifier leave white dust?
The mist carries whatever is in the water - hard tap water means fine mineral dust on every surface. Distilled water stops it completely; evaporative wick units do not have this problem because the minerals stay in the wick.
Do humidifiers use a lot of electricity?
No - even a whole-room unit draws less than a couple of old light bulbs, typically a few dollars over an entire winter. The real cost is the water jugs and the filter wicks, which is where the refill math earns its place.