Dehumidifier Run Cost Calculator

Most people pick a dehumidifier by pints-per-day capacity and never look at how much it costs to run.
A 50-pint Energy Star unit pulls about 500 watts when the compressor is on.
A non-Energy Star 50-pint pulls 700-800 watts for the same job.
Across a humid summer in a damp basement, that gap is real money.

The math is one line:

monthly_cost = (watts × hours_per_day × 30) / 1000 × price_per_kWh

A 500 W dehumidifier running 12 hours a day at 16 cents per kWh costs $28.80 per month.
Run the same unit around the clock in a wet basement and it is $57.60, exactly double, because run time is the only thing that changed.

On the rate field. It asks for cents per kWh, meaning hundredths of whatever currency you have selected at the top of the page. Sixteen is a typical US figure. The UK sits nearer 27 pence, Germany nearer 35 euro cents, and California and Hawaii are well above 30. Your last bill has the real number and it is the only one worth using.

Dehumidifiers do not run continuously even when set to “always on."
They cycle: compressor on for 20-30 minutes to pull moisture, off for 10-20 minutes while the humidistat re-evaluates.
The hours-per-day input is compressor-on time, not how long the unit is plugged in.
A reasonable estimate for a moderately humid space is 8-12 hours per day; very damp basements or summer crawl spaces can push 18-22 hours.

Whole-house dehumidifiers (Aprilaire, Santa Fe, Ultra-Aire) draw 600-900 watts but run less frequently because they share air with the HVAC system and their dryer output gets distributed instead of recycled in one room.
Per pint removed, they use about 30% less electricity than a portable.
The downside is the install cost, which as a rough guide runs a few thousand dollars against a couple of hundred for a portable. Treat any figure like that as approximate: it moves with the region, the year, and whether your ductwork cooperates.

A few practical points.
Bucket-emptying portables and pump-drained portables draw the same wattage; the pump itself adds maybe 2-3 watts when active.
Cold rooms reduce dehumidifier efficiency sharply. A unit rated for 50 pints at 80°F may pull only 20 pints at 60°F, and runs longer to do less work.
If your basement is consistently below 65°F, a desiccant dehumidifier (which uses a different mechanism) outperforms a compressor unit despite higher rated wattage.