Dehumidifier Size Calculator
Find the right dehumidifier capacity based on your room size and humidity level.
List of the Best Dehumidifier:
How to Choose the Right Dehumidifier Size
Choosing the correct dehumidifier size is essential for maintaining a comfortable, mold-free environment. Undersized units run constantly, wearing out prematurely, while oversized units waste energy and cost more upfront. This calculator helps you find the right balance.
1. Understanding Dehumidifier Capacity
Dehumidifier capacity is measured in pints (or liters) of moisture removed per day. A “30-pint” unit can remove 30 pints of moisture from the air in 24 hours under standard testing conditions (usually 80°F and 60% RH).
2. Factors Affecting Sizing
- Room size: Larger rooms hold more moisture and require more powerful units.
- Humidity level: The wetter the air, the harder the unit must work.
- Room usage: Basements, laundry rooms, and bathrooms generate more moisture.
- Ventilation: Poor ventilation increases the moisture load.
- Climate: High-humidity regions require stronger systems.
3. Humidity Level Categories
| Level | Description | Typical Signs |
|---|---|---|
| Lightly Damp | 50–60% RH | Air feels moist, musty smell occasionally |
| Moderately Damp | 60–70% RH | Walls may feel damp, persistent musty odor |
| Very Damp | 70–80% RH | Wet spots visible, condensation on windows |
| Wet | 80–100% RH | Standing water, mold growth, major issues |
4. Sizing Guidelines
These estimates help guide your selection:
- Small rooms (under 500 sq ft): 20–30 pints/day
- Medium rooms (500–1,000 sq ft): 30–50 pints/day
- Large spaces (over 1,000 sq ft): 50–70+ pints/day
5. How the Calculator Works
This calculator multiplies your room's volume (in cubic feet) by a moisture factor:
- Light: 0.005 pints/cu ft
- Moderate: 0.007 pints/cu ft
- Very Damp: 0.009 pints/cu ft
- Wet: 0.011 pints/cu ft
Example: A 15 × 20 × 8 ft basement (2,400 cu ft) that is "very damp" would be:
2,400 cu ft × 0.009 = 21.6 pints/day
6. Efficiency Considerations
- Choose ENERGY STAR units for long-term savings
- Consider units with built-in humidistats and timers
- Auto-defrost features are important for cold spaces
7. Maintenance Tips
- Clean filters monthly
- Empty water bucket or use a hose drain
- Keep airflow unobstructed
8. Common Questions
Q: Can I oversize a dehumidifier?
A: Slightly, yes. It will remove moisture faster. But too large a unit may short-cycle and not dehumidify evenly.
Q: Do I need one in winter?
A: In cold climates, moisture still builds up indoors. Choose a unit with low-temp capability if needed.
Q: What is the ideal indoor humidity?
A: Most experts recommend 40–50% relative humidity (RH) for comfort and mold prevention.
9. Conclusion
A properly sized dehumidifier protects your home from moisture damage, prevents mold, and improves air quality. This tool estimates your needs accurately based on space and conditions. When in doubt, size up slightly — especially in humid areas or for damp basements.