SettingsSettings for this calculationUS
The floor area of the basement or room.
Measure the total floor area needing dehumidification.
How consistently damp the space feels, especially in humid weather.
A musty smell that appears only in summer humidity suggests a lower level; visible standing water suggests you likely need a dedicated sump pump alongside a dehumidifier.
Recommended dehumidifier capacity
13 pints/day
This sizing chart assumes typical conditions — extra factors like an attached laundry area, frequent door traffic to outdoors, or a large uninsulated space can push actual needs higher.
- Room area
- 540 sq ft
They open the calculator with your figures already in it
Dehumidifier Sizing Calculator: 12.96 pints/day — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Show calculation logicHide calculation logic
How this was calculated
Formula source(s)
- Widely published dehumidifier sizing guide (per 500 sq ft): slightly damp = 10 pints, moderately damp = 12, very damp = 14, wet = 16, extremely wet = 22
Inputs used
- Room Area
- 540 sq ft
- Dampness Level
- Moderately damp — musty smell, damp spots noticeable
Intermediate steps
- Room area
- 540 sq ft
Confidence note: This sizing chart assumes typical conditions — extra factors like an attached laundry area, frequent door traffic to outdoors, or a large uninsulated space can push actual needs higher.
What this calculation does not cover
- The calculation takes floor area and nothing else. Moisture sits in the air volume, not on the floor plate, so a basement with a 3.5 m (11.5 ft) ceiling and a 1 m (3.3 ft) crawl space of the same footprint return the same answer, and neither the extra air nor the extra wall and slab surface behind it is in the number.
- The dampness level is a description of how the space feels, not a measured moisture load. Nothing here counts the actual sources - an unvented dryer, a bare-earth crawl space floor, an open sump, an adjoining laundry or shower, occupants, or humid outside air leaking in at the rim joist and the stair door. Two rooms of the same area carrying the same rating can differ several times over in the water they give up in a day.
- The per-500-sq-ft rate is applied strictly linearly, so 2,000 sq ft (186 m²) returns exactly four times the 500 sq ft (46 m²) figure. Published sizing tables do not scale that way - pints needed per unit of floor area falls as the space grows - so the further past 500 sq ft (46 m²) you go, the more this overstates the machine. At the largest area it accepts, on the wettest setting, it returns over 200 pints a day, far beyond any single residential unit.
- Air temperature is not an input. A refrigerant dehumidifier's plate rating is measured in warm air and its real extraction falls off sharply as the space gets colder, to the point where the coil frosts and the machine spends part of its cycle defrosting rather than pulling water; a basement, crawl space or garage that stays cold usually wants a low-temperature or desiccant unit, not a bigger conventional one. The pint figures here are also not tied to any stated test standard, and the standard changed - older ratings were taken in warmer air than current ones - so a 12-pint recommendation and a machine plated at 12 pints are not necessarily the same amount of water.
- This is a capacity figure only. It does not set a humidity target, estimate run hours or condensate volume, choose a drain route, or check the circuit will carry the machine, and it does not size drainage, a sump, grading or a vapour barrier. Where the 'extremely wet' level applies - standing water or active seepage - water is arriving faster than a dehumidifier is built to remove it, and the water path is the job before any capacity number means anything.
Add the equipment this sizes
This result is a specification — 13 pints/day — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-02 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Widely published dehumidifier sizing guide (per 500 sq ft): slightly damp = 10 pints, moderately damp = 12, very damp = 14, wet = 16, extremely wet = 22
Cite this page
Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.