Counts the quiet part
Fan-only draw does not disappear when the compressor cycles off.
Free, local energy calculator
Know what your dehumidifier is really costing.
Turn watts, compressor cycling and your own electricity rate into a clear seasonal cost. Comparing an old unit? See whether lower energy use repays the replacement price while the comparison still makes sense.
- No signup
- No tracking
- Runs in your browser
Compares the job
Capacity and IEF checks keep low wattage from posing as equal performance.
Tests the purchase
See payback and net savings inside the years you expect to own it.
Your calculation
Start with the numbers you can verify.
No live tariff guesses. Use the delivered price from your bill and adjust every assumption.
Current
- Used day
- Active month
- Input
Replacement
- Used day
- Active month
- Input
Before you decide
Assumptions used
Planning estimate, not a diagnosis. This tool cannot identify a leak, mold problem, correct electrical work, choose equipment for a building, or predict real-world water removal.
The honest method
Nameplate watts are only the beginning.
A dehumidifier can draw different power while compressing, running its fan, defrosting or waiting. DryCost keeps the uncertain parts visible.
Energy on a used day
(active watts × active hours + fan watts × remaining hours) ÷ 1,000
Selected-season cost
daily kWh × used days × your price per kWh
Simple energy payback
net purchase price ÷ annual electricity savings
Compare output, not just input
A 350-watt unit is not automatically “more efficient.”
It may simply remove less moisture. Integrated Energy Factor (IEF) reports liters removed per kWh under label test conditions. For comparable capacity, higher is better.
U.S. ENERGY STAR portable criteria reviewed July 19, 2026≤25 pints/day: 1.70 L/kWh · 25.01–50: 2.01 · above 50: 3.30Check the official criteria
Worked example
The cheaper-looking machine can take years to earn its price.
An older 600 W unit is scheduled for 12 hours, with the compressor active 70% of the time and a 40 W fan draw. A 450 W replacement is expected to run at full power 50% of that schedule. Both operate daily for six damp months at €0.30/kWh.
The replacement saves electricity, but the €250 purchase still needs roughly two years to break even. Change the cycling assumption and the answer moves—exactly why it belongs beside the result.
- 1Use your delivered tariff
Not a national average that can age or ignore delivery charges.
- 2Measure when practical
A representative smart-plug day is stronger than an assumed duty cycle.
- 3Run a high and low case
If cycling is uncertain, calculate both ends before buying.
Know the boundary
Useful arithmetic. No false certainty.
Persistent damp, water ingress, unusual odors or visible mold need the appropriate qualified help; a calculator cannot identify the cause.
Capacity and IEF use controlled conditions. Temperature, humidity, airflow, defrosting, settings and maintenance change real performance.
The break-even number excludes reliability, repairs, disposal, financing, noise, heat added to the room and product life.
Plain-language answers
Dehumidifier cost questions, answered.
How much does a dehumidifier cost to run?
Multiply energy use in kWh by your delivered electricity price. For a cycling unit, include both compressor-active power and fan-only power rather than assuming full wattage for every scheduled hour. Your room and settings determine the real pattern.
What duty cycle should I enter?
Enter the share of scheduled time when the compressor runs at full power. The visible 60% starting value is only an example. A plug-in meter measured across a representative day gives a stronger estimate; otherwise run more than one scenario.
Does lower wattage mean a unit is more efficient?
Not by itself. Compare units with similar rated capacity and use IEF in liters per kWh when available. Higher IEF means more rated moisture removal per unit of electricity under label test conditions.
When does a replacement pay for itself?
Simple energy payback is net purchase price divided by annual electricity-cost savings. The result is incomplete if the units do different work or if reliability, repairs and expected life matter to the decision.
Does anything I enter leave my device?
No calculator input is uploaded. The math runs in your browser. The hosting provider still receives ordinary technical requests needed to deliver the page, and clicking the optional Ko-fi link takes you to another site.
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