Model
Lg DLEX3900*
Rank #150 means 149 of the 615 clothes dryer models we track cost less to run each year; the 62nd efficiency percentile means it uses less energy for its size than 62% of those models.
What does the Lg DLEX3900* cost to run per year?
The Lg DLEX3900* costs about $113 a year to run, which beats most of the 615 clothes dryer models we track; it ranks #150. Its size-adjusted efficiency percentile of 62 is comfortably above the class median. Its CEF of 3.94 reflects combined energy factor, one of the class's core efficiency levers.
Immediately around it on the leaderboard, the Lg DLE7100* at $113/yr runs a little cheaper and the Lg DLEX3700* at $113/yr runs a little more, a sense of how tightly models are packed at this point in the ranking. A clothes dryer typically stays in service for somewhere around 13 years; over that span, the Lg DLEX3900*'s $113/yr adds up to roughly $1469 in electricity alone, before purchase price or repairs.
Also sold as: Lg DLE3090*.
By the numbers
The Lg DLEX3900* normalized against its whole class, so each figure means something.
What it costs you over time
Running cost is an every-year number, so it compounds. At $113/yr, here is what the Lg DLEX3900* adds up to before purchase price, water, or repairs enter the math.
Left running for a decade at today's US average rate, the Lg DLEX3900* costs about $1130. That is roughly $0 less than the class median, which would run closer to $1130 over the same ten years.
How the Lg DLEX3900* compares
The clothes dryer class we track runs from $23 to $128 a year. At $113/yr, it sits right on the class median of $113, and it is about $90 a year more than the cheapest clothes dryer to run at $23.
What drives its running cost
At 7.4 cu ft, the Lg DLEX3900* is a small clothes dryer for its class, which spans 3.8 to 9.2 cu ft with a median of 7.4 cu ft, and smaller clothes dryer models generally cost less to run for the same job, all else being equal. Beyond size, its CEF of 3.94, above the class median of 3.93, is the class's own efficiency yardstick, combined energy factor, and it is what separates two similarly sized models with different running costs.
- Heat source and Combined Energy Factor (CEF). Heat-pump dryers recycle heat instead of generating it fresh with a resistance coil, and typically use meaningfully less electricity per load than a conventional resistance dryer, at the cost of a longer cycle; CEF is the federal figure that captures this.
- Drum capacity. A larger drum can dry a bigger load per cycle, but it also usually needs more energy per cycle to heat the extra air volume.
Common questions
Is the Lg DLEX3900* cheap to run?
Yes. Its $113/yr running cost puts it at rank #150 of 615, below what most clothes dryer models we track cost to run.
How much does the Lg DLEX3900* cost per month?
About $9.39 a month, which is the $113 annual estimate spread across twelve months at the US average rate of $0.1856/kWh. Your own bill scales with your local electricity rate and how heavily you use it.
How is this running-cost figure calculated?
The formula is annual kWh times price per kWh: 607 kWh from ENERGY STAR times the US average of $0.1856/kWh comes to about $113 a year. It covers electricity only, not the purchase price, water, or installation.
How efficient is the Lg DLEX3900* for its size?
62nd percentile once size is factored in, a fairly typical result for the class.
Cheaper to run in the same class
| Rank | Model | Cost/yr |
|---|---|---|
| 143 | Lg DLE7100*7.3 cu ft | $113 |
| 142 | Lg DLEX5005*7.4 cu ft | $113 |
| 141 | Lg DLE7050*7.3 cu ft | $113 |
| 140 | Lg DLEX4370*7.4 cu ft | $113 |
| 139 | Lg DLEX7200*7.3 cu ft | $113 |
Source
ES_1118034_DLEX3900*_02122018095146_70170997View certified clothes dryer listingsENERGY STAR data as of July 2026Lg and DLEX3900* are used here for identification only and are not endorsements. Figures are computed by WattWise Labs from public ENERGY STAR data, not measured in our own lab.