What Does an Air Purifier Really Cost to Run?

How many units does an air purifier use?

Units (kWh) = watts ÷ 1,000 × hours per day × days.

Use the wattage printed on your purifier or its product page. That figure is usually the maximum, at top speed. On auto or sleep mode it draws less, so treat the max figure as the worst case.

Air purifier electricity cost per month

Monthly cost = units × your per-unit rate.

Delhi bills use slabs, and your rate depends on your total household use and any subsidy. Enter the per-unit rate from your own bill rather than a city average. Tariffs are set by DERC and shown on your discom bill.

At an example ₹8/unit: 21 W × 12 h × 30 days → ₹60/month; the same unit at 24 h → ₹121/month.

Bottom line: for a small purifier, electricity is the smaller part of the running cost. Filters are the line to watch.

Should you run it 24 hours? What it costs

Doubling the hours doubles the electricity: compare ₹60 with ₹121 at the example rate above. The US EPA notes that increasing the amount of time an air cleaner runs will also increase air filtration, and that higher fan speeds filter more air. Longer running can also use up filter life faster, so put your real hours into the calculator.

Air purifier filter replacement cost per year

Filter cost per year = filter price × (months you run it per year ÷ filter life in months).

Filter life: use the maker's figure. It is usually written as "up to" X months, which makes it a maximum, not a promise. The EPA says all filters need regular replacement — a dirty, overloaded filter will not work well — and to replace filters according to the manufacturer's recommendations.

Check the replacement filter's price before you buy the purifier. Over a few years, the filters can cost more than you'd guess.

Example price, checked 9 Nov 2026 (IST): Philips FY0900/30 filter, ₹2,370 on Philips India's store. This is an example, not a recommendation. Prices change; a second listing for the matching purifier showed ₹9,899, so treat list prices as a snapshot.

The real cost of owning an air purifier: 1, 3 and 5 years

Total = purchase price + fees + (yearly electricity × years) + (replacement filters × filter price). Replacement filters = (total months of use ÷ filter life, rounded up) − 1, because the first filter comes in the box.

Example inputs (checked 9 Nov 2026): a ₹9,995 purifier, rated 250 m³/h CADR and 21 W at max — the Philips AC0920/60 figures listed on Philips India's store. It is an example, not a recommendation. Its filter: ₹2,370, rated "up to 1 year". Run 12 h/day at an example ₹8/unit.

How long a filter actually lasts depends on your air and your hours, so try both filter-life settings in the calculator.

What CADR do you need for your room?

CADR (clean air delivery rate) is how much filtered air the purifier puts out. A higher CADR covers a bigger room. The EPA notes it is typically measured at the air cleaner's highest speed, so at lower speeds you get less.

Quick rule for an 8 ft ceiling: EPA's portable air cleaner sizing table sets a minimum CADR (cfm) of about two-thirds of the floor area in sq ft (100 sq ft → 65 cfm, 200 → 130, 300 → 195, 400 → 260). That matches 5 air changes per hour at an 8 ft ceiling.

Indian boxes usually list CADR in m³/h. Convert: area (m²) = length (ft) × width (ft) × 0.0929; volume (m³) = area × ceiling height (ft) × 0.3048; CADR needed (m³/h) = volume × air changes per hour (ACH). ACH your purifier gives = its CADR (m³/h) ÷ room volume.

The CDC suggests aiming for 5 or more air changes per hour where possible, and notes that 5 ACH is what portable air cleaners provide when properly sized to EPA guidance. Use that as a sizing target for the calculator; this page does not make health claims.

If you buy too small, the purifier cannot keep up with the room. If you buy much larger than you need, you typically pay more upfront and more to run it, through extra energy use and pricier filters.

Can you afford it on your salary? EMI vs paying upfront

EMI = P × r × (1 + r)^n ÷ ((1 + r)^n − 1), where r = annual rate ÷ 12 ÷ 100 and n = months. At 0% ("no-cost"), EMI = P ÷ n.

Ask about processing fees and add them to the price. "No-cost" refers to the interest. It does not promise the deal has no other charges.

EMI % of take-home = EMI ÷ take-home × 100. What's left = take-home − EMI. The running costs come on top: electricity each month, plus about filter cost ÷ 12 if you put money aside for filters.

Example: ₹9,995 purifier, take-home ₹40,000. A 12-month 0% EMI is ₹833 (2.08% of take-home). At an example 14% for 12 months, EMI is ₹897 (2.24%).

Before you buy: a 4-point cost checklist

1. Measure the room, then check the CADR in m³/h against your room's volume.

2. Find the replacement filter's price and rated life on the brand's own site.

3. Note the max wattage and plug it into the calculator with your bill's per-unit rate.

4. Run the 3-year total, not just the price tag. If you are paying in EMIs, check the EMI as a % of your take-home.

The EPA advises avoiding air cleaners that intentionally produce ozone. This page covers cost only. For what purifiers can and cannot do, read the EPA Guide to Air Cleaners in the Home.