Dehumidifier Testing Standards: How AHAM Ratings Are Set

What the pint rating actually means

The pint rating on a dehumidifier label is the amount of water the unit can remove in 24 hours under a specific set of test conditions. The U.S. Department of Energy (DOE) defines these test conditions and the measurement method. As stated on the ENERGY STAR testing page, capacity is defined as the amount of water removed per day at test conditions and is reported in pints per day. This is the number you use to compare models. For a deeper look at what that number means in practice, see our guide on pint ratings.

The test procedure evolved from earlier industry standards, often referred to as the AHAM DH-1 protocol. While the DOE now sets the official method, the goal remains the same: give consumers a consistent way to compare how much moisture a unit can pull from the air, regardless of brand or model.

Why capacity ratings dropped in 2020

Before 2020, portable dehumidifiers were tested at 80°F, which is warmer than most basement environments. The DOE revised the test to 65°F to better reflect real-world basement conditions. According to ENERGY STAR, this 15°F reduction means a dehumidifier tested to the new procedure will likely report a smaller capacity than when tested to the old procedure.

This change does not mean the unit performs worse. It means the rating is based on more realistic conditions where the air holds less moisture. The table below shows the approximate correlation between old and new portable ratings, as published by ENERGY STAR.

Energy efficiency: IEF replaces EF

Energy efficiency for dehumidifiers is measured by the Integrated Energy Factor (IEF), which replaces the older Energy Factor (EF). The ENERGY STAR page explains that IEF is expressed in liters of water removed per kilowatt-hour of energy consumed (L/kWh). Unlike EF, IEF includes the energy the unit uses when it cycles off, giving a more accurate picture of annual energy use. To learn more about this metric, see our article on IEF.

When comparing models, look for a higher IEF value. The DOE energy conservation standards set minimum IEF levels for each capacity class. For example, a dehumidifier with a capacity of up to 35 pints per day must meet at least 1.35 liters per kWh, according to the DOE. Higher IEF numbers indicate a more efficient unit, which can reduce your electricity bills over time.

Why you can trust the comparison

Because every manufacturer uses the same DOE test procedure, a 30-pint model from one brand removes the same amount of water under the same conditions as a 30-pint model from another brand. This uniformity is what makes published pint ratings a reliable way to compare units. The key is to check that the rating was set under the current 65°F test, not an older 80°F test. Most products sold today are labeled with the new rating, but if you are replacing an older dehumidifier, use the mapping table above to translate the old rating to the new one.

Standardized testing also applies to the energy efficiency figure. The DOE sets the test procedure and the minimum IEF standards, so an ENERGY STAR certified model has met a specific efficiency threshold. This is independent of capacity, so you can compare efficiency across different pint classes. For practical tips on choosing an efficient model, see our guide to ENERGY STAR dehumidifiers.

How to choose the right pint capacity

Once you understand the rating, you still need to size the unit to your space. The ENERGY STAR buying guidance provides capacity recommendations based on the dampness level and room size. For a slightly to moderately damp space under 2,000 square feet, they suggest 20 to 30 pints per day. For a very damp space of the same size, 25 to 40 pints, and for a wet space, 30 to 50 pints. Larger rooms require higher capacities, as shown in their chart.

Remember that these recommendations are for portable units. Whole-home dehumidifiers are tested and sized differently, and are typically installed by a professional. If you need a whole-home system, consult the whole-home buying guidance for more detail. You can also use our sizing guide to match capacity to room dimensions.

What to pick for your use

Questions

What does the AHAM DH-1 standard refer to?

The AHAM DH-1 standard is the original industry test procedure for measuring dehumidifier water removal capacity. It was developed by the Association of Home Appliance Manufacturers. Today, the U.S. Department of Energy defines the official test method, which is closely aligned with the DH-1 approach, and all manufacturers must follow the DOE procedure. For more on how this translates to real-world performance, see our guide on pint ratings.

Why do new dehumidifiers have lower pint ratings than older ones?

Because the DOE changed the test temperature from 80°F to 65°F in 2020 to better reflect typical basement conditions. Cooler air holds less moisture, so a unit removes less water per day in the test. The underlying performance is the same, but the reported capacity is lower.

Can I compare the pint rating of two different manufacturers?

Yes, as long as both units are rated under the current DOE test procedure. The test conditions are standardized, so a 30-pint model from any brand removes the same amount of water at 65°F and 60% relative humidity (or the exact DOE setpoints). This is the whole point of the standardized test.

What is the difference between IEF and EF?

EF, the Energy Factor, only measured energy used while the compressor was running. IEF, the Integrated Energy Factor, includes energy consumed during the off cycle, standby power, and defrost mode. IEF gives a more accurate estimate of annual energy use and is the required metric for all new dehumidifiers since June 2019. To dive deeper, check out our comparison of IEF and EF.

How do I know if a dehumidifier is tested at the new 65°F condition?

Check the product label or the energy guide. If the unit was manufactured after June 2019, it must use the new test procedure. The capacity listed on the box is the new rating. If you are replacing a unit bought before 2020, refer to the capacity correlation table in this article to translate the old rating.

Should I oversize my dehumidifier?

ENERGY STAR recommends it is better to oversize than undersize. A unit with too little capacity will run continuously and may not keep humidity low enough to prevent mold. Sizing up by 10 to 20 percent from the chart recommendation gives you a safety margin, but do not go so large that the unit short-cycles and fails to dehumidify effectively.