Define the complete drying session
Start the observation when wet laundry is placed in the room and end when it reaches the dryness you accept. Record load size, washer spin setting, room conditions, dehumidifier setting, open or closed doors and windows, and whether a separate fan or heater operates.
A two-hour reading that stops before the clothes are dry is not directly comparable with a full dryer cycle. The outcome boundary matters as much as the watts.
Calculate one illustrative session
At a hypothetical 450 W average for six hours, energy is 0.45 × 6 = 2.7 kWh. At $0.18/kWh, the session costs $0.486, rounded to $0.49. Twelve equal loads would cost $5.83.
If the same device averages 300 W because it cycles, the six-hour result is 1.8 kWh and $0.32. If drying takes ten hours at that average, cost rises to $0.54. Use cumulative kWh for the complete session rather than combining a guessed duty cycle with a guessed drying time.
A fuller washer spin can change the starting moisture and the hours needed. Record that setting before crediting the dehumidifier for a shorter session; otherwise two loads with different starting water content are not an equivalent comparison.
| Average input | Time to chosen dryness | Energy | Cost at $0.18 |
|---|---|---|---|
| 300 W | 6 hours | 1.8 kWh | $0.32 |
| 450 W | 6 hours | 2.7 kWh | $0.49 |
| 300 W | 10 hours | 3.0 kWh | $0.54 |
Count any other equipment once
Add a circulation fan or heater only when it actually runs for the drying session. Calculate each device on its own schedule, then sum kWh. If one plug meter captures the entire power strip, do not add the devices again.
Do not compare only the heating element of a clothes dryer with the complete dehumidifier session. For an electric dryer, use per-cycle kWh from the label, product data or a suitable measurement, and compare loads of similar size and starting moisture.
Manage the room as well as the electricity
ENERGY STAR identifies indoor laundry drying as a high-moisture condition and advises reducing moisture sources where possible. Follow dehumidifier placement, drainage and electrical-safety instructions, and do not let wet laundry obstruct the appliance.
Watch for persistent condensation or building moisture problems. A lower per-load electricity figure does not prove that an indoor routine is suitable for every apartment, fabric or season. Use the result as a budget record, not a mold-prevention guarantee.
Choose your next step
Continue with the question that matches your next decision:
Sources & further reading
Numerical examples are illustrative unless explicitly described as measured. This guide does not claim hands-on product testing. Read the methodology and editorial disclosure.