Air Purifier Running Cost Calculator

Table of contents

• How to use
• Common mistakes
• Definitions
• Methodology
• Limitations & assumptions
• Sources

Watt: A unit of electrical power. Purifier power is the amount of power the purifier draws while running.

kWh (kilowatt-hour): The electricity used by 1,000 watts for one hour. A 50-watt purifier running for 20 hours uses 1 kWh.

Electricity price: The amount charged for each kWh of electricity, usually shown on an electric bill in dollars or cents per kWh.

Replacement filter price: The cost of the complete filter set that is normally replaced together.

Estimated yearly filter cost: The average cost of filters over one year, based on the entered price and replacement interval.

Estimated ownership cost for planned time: Estimated electricity expense plus the cost of whole replacement filter sets due during the chosen time.

Mistake: Entering 50 as Electricity price when your bill says 16 cents per kWh.
Fix: Enter 0.16 because this field uses dollars per kWh.

Mistake: Using the purifier's maximum power for Purifier power even though it usually runs on a lower setting.
Fix: Use the average watts you expect it to draw, or measure it with a plug-in power meter.

Mistake: Treating Hours used each day as weekly hours.
Fix: Enter the daily average from 0 through 24; divide weekly hours by 7 if needed.

Mistake: Entering one filter's price when several filters are replaced together in Replacement filter price .
Fix: Enter the price of the full replacement set normally changed at the same time.

Mistake: Expecting an exact purchase schedule from Replacement filters needed for planned time .
Fix: Treat it as an estimate based on the entered interval; dust, odors, and the purifier manual can change replacement timing.

• Electricity use is estimated from one entered watt value and average daily hours. Auto mode, changing fan speeds, standby power, and dirty filters can make actual use different.
• The electricity estimate uses 365 days per year and the entered electricity price. Utility fees, taxes, tiered rates, and future price changes are not added.
• Filter cost is based on the price and schedule you enter. Real replacement timing can vary with air quality, room conditions, and the purifier manual.
• The planned-time estimate assumes the purifier begins with a fresh filter and counts a replacement due exactly at the end of the selected time.
• The calculator estimates operating and filter expenses only. It does not include the purifier purchase price, repairs, shipping, or sales tax.

Electricity estimate

The calculator changes watts into kilowatts, then multiplies by average hours used each day. It multiplies daily electricity use by your entered price to estimate daily cost, and by 365 for yearly cost.

daily_energy_kwh = (power_watts / 1000) * hours_per_day

daily_electricity_cost = daily_energy_kwh * electricity_rate

annual_electricity_cost = daily_electricity_cost * 365

monthly_electricity_cost = annual_electricity_cost / 12

Filter and ownership estimate

Average yearly filter cost spreads the entered replacement price across the entered replacement schedule. The yearly and monthly ownership figures add this average filter expense to electricity expense.

annual_filter_cost = filter_price * (12 / filter_interval_months)

annual_total_ownership_cost = annual_electricity_cost + annual_filter_cost

monthly_total_ownership_cost = annual_total_ownership_cost / 12

For planned time, the calculator counts whole replacement sets using ceiling rounding. This assumes a fresh filter at the start and counts one due at the end of the selected period.

planned_filter_replacements = ceil((planned_years * 12) / filter_interval_months)

planned_ownership_cost = (annual_electricity_cost * planned_years) + (filter_price * planned_filter_replacements)

Worked example

With 50 watts, 12 hours each day, and $0.16 per kWh, daily use is 0.6 kWh and yearly electricity cost is $35.04. With $30 filters replaced every 6 months, average yearly filter cost is $60, so estimated yearly ownership cost is $95.04.

Calculation choices

Dollar results are estimates rounded to cents for display. Filter replacements are rounded up only for the planned-time estimate; the yearly filter result is an average. Zero electricity price or zero filter price is treated as a real zero cost, not guessed.