Dehumidifier sizing
What size dehumidifier do I need?
3-step calculator Based on AHAM DH-1-2022 Reviewed by the WhatSize editorial team
Last reviewed June 2026 • Sources: AHAM DH-1, ENERGY STAR, 10 CFR 430
Quick answer
Dehumidifier size is measured in pints per day and depends on your room's square footage, ceiling height, and moisture level. A 1,000 sq ft basement with normal dampness needs a 30-50 pint unit; very damp conditions need 50-70 pint. The 3-step wizard below applies the AHAM DH-1-2022 standard to your inputs.
How big is your room?
Don't worry about being exact — give us your best estimate.
How damp is your space?
Choose the option that best matches your situation.
Slightly: feels muggy on humid days • Moderate: musty smell, RH 60–70% • Very: damp walls, condensation • Wet: standing water or active leaks
Based on AHAM DH-1-2022, Section 5 (Capacity Rating)
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Got a result that doesn't match your situation?
Adjust your inputs above and re-run the calculator. Most users find their spec falls within 1-2 sizes of the recommendation.
Formula
Base Pints = AHAM DH-1 Table[sqft bracket][dampness] × Ceiling Factor + Basement(+5) + Laundry(+5)
→ Round up to nearest standard size (22/35/50/70 pints)
About this calculation
This is a simplified sizing tool based on published industry standards, not a full professional audit.
Accuracy depends on your input — subjective factors like dampness level or insulation quality are estimates. Our formulas include a safety buffer that may result in oversizing for some situations (slightly higher cost, but safer than undersizing).
Local variables (climate zone, altitude, insulation levels, building codes) can affect real-world sizing needs. Standards are re-checked quarterly — see our Editorial Policy.
Common scenarios for dehumidifier sizing
If your situation matches one of these, jump straight to a detailed guide:
Frequently asked questions
What size dehumidifier do I need for my basement?
Match pint capacity to square footage and dampness level. A 1,500 sq ft moderately damp basement typically needs a 50-pint unit; a very damp 1,500+ sq ft basement needs 70 pints. AHAM DH-1-2022, together with the DOE 2019 test rule (10 CFR 430), rates capacity at 65°F and 60% RH for more realistic basement conditions.
How many pints per day do I need?
Rule of thumb: 10 pints per 500 sq ft for moderately damp spaces, 10 pints per 250 sq ft for very damp spaces. Add 5 pints if a bathroom or laundry is nearby. The wizard above factors in your room size and dampness level.
Is a 50-pint or 70-pint dehumidifier better?
70-pint models remove more moisture per day but use more energy. Choose 50-pint for standard basements under 2,000 sq ft with moderate dampness. Choose 70-pint for very damp spaces, larger areas, or active moisture intrusion.
Where should I place my dehumidifier?
Place it in the dampest area with at least 6 inches of clearance on all sides for airflow. Elevate it on a block if your basement floods. Empty the bucket daily, or connect a drain hose for continuous operation.