What Size Dehumidifier for a 1,500 Sq Ft Basement? (2026 Sizing Answer)

“1,500 sq ft basement” is one of the most-searched dehumidifier questions for a reason: it’s the most common basement size in American homes, and it’s exactly the size where the wrong answer is expensive. Too small and the unit runs forever without catching up. Too big and you’ve overspent by $800. Here’s the exact answer and the math behind it.

The direct answer: 50–70 AHAM pints

For a 1,500 sq ft basement in a typical climate with typical dampness: 50 to 70 AHAM pints per day. The cleanest single pick is the AprilAire E070 Pro — 70 AHAM pints, rated for spaces up to 2,200 sq ft, ~$1,550–1,770.

Why the range instead of one number? Because square footage is only one of three inputs. The other two — dampness level and temperature — move the answer within that range, and sometimes out of it.

The three inputs that set the size

1. Square footage (1,500 sq ft — fixed). The rough rule is ~10 AHAM pints per 500 sq ft in humid conditions, which puts 1,500 sq ft at ~30 pints as a floor. But that’s the floor for living space at 80°F — basements need more, which brings us to input two.

2. Temperature. The AHAM test runs at 80°F. Your basement runs at 60–70°F, maybe cooler. Compressor dehumidifiers lose output as temperature falls — the coils get colder, frost becomes a risk, and the machine spends energy defrosting instead of dehumidifying. A 70-pint AHAM unit in a 65°F basement behaves more like a 50-pint unit. This is the single most underappreciated factor in basement sizing, and it’s why basement guidance always runs one step above the living-space math.

3. Dampness level. Be honest about yours:

• Slightly damp (55–60% RH, no smell, no visible moisture): 50 AHAM pints suffices
• Moderately damp (60–65% RH, faint mustiness after rain): 55–70 AHAM pints
• Very damp (65–70%+ RH, musty smell, visible damp spots, efflorescence on walls): 70–80 AHAM pints
• Wet (standing water history, 70%+ RH sustained): fix the water intrusion first — no dehumidifier outruns a leak — then 70–80 AHAM pints

For the full climate-zone tables behind these rules, see our sizing by climate zone guide.

The picks for a 1,500 sq ft basement

The direct answer: AprilAire E070 Pro. 70 AHAM pints, 5-year warranty, Energy Star rated, 10-ft drain hose included, ~$1,550–1,770. Rated for up to 2,200 sq ft, which gives a 1,500 sq ft basement exactly the 20–30% headroom the pros recommend. This is the unit when you want the question settled.

The budget answer: AlorAir Sentinel HD55. 55 AHAM pints (120 marketed — remember the AHAM vs saturation translation), ~$506–638. Right-sized for a moderately damp 1,500 sq ft basement, and the value is genuinely excellent. The tradeoffs: 1-year-ish warranty tier, noisier, less efficient than the AprilAire.

The “very damp basement” answer: AprilAire E080. 80 AHAM pints (65 DOE), ~$1,750–1,900, Energy Star Most Efficient 2025. When the basement is cool, musty, or in a humid climate, the step up from 70 to 80 AHAM pints is cheap insurance.

What about a portable? A 50-pint portable (~$250–350) can work for a 1,500 sq ft basement that’s only slightly damp — but portables are rated at warmer conditions, lose more output in cool basements, and need emptying or a hose. For a primary basement moisture problem, a plumbed whole-house-style unit is the grown-up answer. Our portable vs whole-house comparison has the full economics.

The AHAM trap, 1,500-sq-ft edition

This specific search is where the saturation marketing numbers do the most damage. A buyer searches “dehumidifier for 1500 sq ft basement,” finds a “120-pint” unit for $600, and reasonably concludes it’s double what they need. It’s 55 AHAM pints — adequate for a moderately damp basement, undersized for a wet one, and definitely not double anything.

The rule, one more time: AHAM pints in, AHAM pints out. Every recommendation on this site, every row in our comparison tables, and our capacity sizer tool all speak AHAM. If a product page won’t show you the AHAM line, that’s information too.

Worked examples: three 1,500 sq ft basements

Same square footage, three different answers — this is why the dampness and temperature inputs matter:

The Johnsons — Columbus, Ohio. Finished basement, 68°F, 58% RH, faint mustiness after heavy rain. Moderately damp, mild climate, reasonably sealed. Math: 1,500 sq ft → ~30-pint floor, one step up for basement temperature, no extreme dampness multiplier. Answer: 55 AHAM pints — the AlorAir Sentinel HD55 at ~$506–638 handles it with headroom to spare. Total spend stays under $700 even with a condensate pump added.

The Patels — Charlotte, North Carolina. Unfinished basement, 66°F, 64% RH, musty smell all summer. Humid Southeast climate, moderate-to-high dampness, cooler slab. Math: base 30 pints, up a step for temperature, up another half-step for humidity and climate zone. Answer: 70 AHAM pints — the AprilAire E070 Pro at ~$1,550–1,770. The 5-year warranty and honest AHAM rating matter here because this unit will work hard every summer for a decade.

The Garcias — Houston, Texas. 1,500 sq ft basement, 63°F, 70% RH, visible damp spots on one wall. Gulf Coast humidity plus a cool slab plus active moisture signs. Math: base 30, up for temperature, up again for dampness, up again for climate. Answer: 80 AHAM pints — the AprilAire E080 at ~$1,750–1,900. And critically: the damp wall gets investigated first. No dehumidifier outruns active water intrusion — fix grading, gutters, or foundation seepage before sizing anything.

Notice the pattern: nobody in these examples needed more than 80 AHAM pints for 1,500 sq ft, and nobody was well-served by less than 55. The 50–70 band covers the vast middle; the edges are about honesty regarding dampness, not about square footage.

A note on ceiling height and open floor plans

The square-footage rules assume standard 8-foot ceilings. A 1,500 sq ft basement with 10-foot ceilings holds 25% more air — nudge one step up. Similarly, a basement that’s wide open to the floor above (open stairwell, no door) is really dehumidifying more than 1,500 sq ft of air volume, because humid air migrates freely. In that case, consider whether you’re actually solving a basement problem or a whole-house problem — a ducted whole-house unit tied into the HVAC may be the better answer than a bigger basement box.

Installation notes for basements

Basements are the easiest dehumidifier install in the house, which is part of why they’re the most common:

• Drainage: A floor drain or laundry sink is often nearby — gravity drainage with the included hose usually just works. No drain? A condensate pump ($150–500) or a pump-equipped unit solves it.
• Placement: Central, with clear airflow on all sides. Don’t tuck it in a corner behind the water heater — it needs to breathe to do its job.
• Ducting (optional): Freestanding works fine for most basements. Ducted installation makes sense when you’re treating the basement plus the floors above as one system.
• Setpoint: 45–50% RH. Lower wastes energy; higher invites mold. Let it run for a week before judging — the first few days it’s draining months of accumulated moisture from concrete and framing.

For the complete budget once you’ve picked the size, our installation cost guide and monthly energy cost guide close the loop on total ownership cost.