Quick answer: Compare replacement-filter spending and electricity separately, after checking that a purifier is large enough for your room. A cheap annual filter bill does not make an undersized purifier good value. The examples below show how to build a budget from dated US manufacturer prices and explicit assumptions.
Reference prices checked September 22, 2026. This is a planning worksheet, not a set of measured household bills or a ranking of the cheapest air purifiers. It excludes purchase price, tax, shipping and discounts.
Start with the room, then compare the recurring bill
Use our room-size and smoke-CADR calculator to work out a size target before comparing running costs.
ENERGY STAR sizing guidance starts with room area and notes that higher ceilings can require more CADR.
For a chosen air-change target, required clean-air delivery in cubic feet per minute is room area in square feet × ceiling height in feet × air changes per hour ÷ 60. For example, 400 square feet with an 8-foot ceiling at a hypothetical 4.8 air changes per hour requires 256 CFM. This is a volume calculation, not a guarantee of performance in an occupied room.
Use the same particle category and test conditions when comparing CADR. Do not compare one machine’s pollen CADR with another’s smoke CADR, or assume a headline coverage figure at one air change per hour means the same thing as a figure at 4.8. Likewise, a published maximum cleaning rate does not establish the cleaning rate at a quiet fan setting.
Replacement-filter budgets: one versus two changes a year
These are equal-frequency spending scenarios, not a claim that every model needs the same replacement schedule. Follow the instructions for your exact model and adjust for use and filter condition. The amount below is an annualized budget; it is not necessarily the cash you spend in your first year, because a new appliance includes its initial filter.
| Exact filter option | Reference price | One complete replacement/year | Two complete replacements/year |
|---|---|---|---|
| Coway Airmega 400/400S Max2 set, SKU 3104756; two filters for the two sides | $129.00/set | $129.00 | $258.00 |
| Coway Mighty2 AP-1512N Fresh Starter option | $69.99 | $69.99 | $139.98 |
| Levoit Core 600S-P Original, LRF-C601-WUS | $59.99 | $59.99 | $119.98 |
Manufacturer sources: Airmega 400/400S Max2 set, Mighty2 Fresh Starter and Core 600S-P Original filter. Coway’s 400 filter page lists 12 months; its Mighty2 page lists 6–12 months. Levoit notes that usage and pollution can change the replacement interval. The two-change column is a sensitivity scenario, not a universal manufacturer instruction.
The Levoit price belongs to the Original option. Other versions on its site have different prices; check the complete filter name before comparing. The Mighty2 filter price is not a price for the older AP-1512HH. For the Airmega 400, do not double the set price again simply because the machine has two sides.
Calculate electricity with your own usage
Annual electricity cost = average operating watts ÷ 1,000 × hours per day × 365 × your electricity price per kWh. A plug-in meter measured over a representative period can provide your own average draw. A published rated-power figure is a different input; it should not be labelled measured medium-speed consumption.
For an illustration only, assume a constant 50 W draw and electricity at $0.15/kWh. Twelve hours per day gives 219 kWh and $32.85 per year. Twenty-four hours gives 438 kWh and $65.70. These are hypothetical inputs, not a claim about a particular purifier or the US average electricity rate. Changing fan speed or automatic operation changes the average draw.
Enter your own three inputs before adding electricity to the filter budget. If your average wattage is unknown, keep electricity as a separate scenario until you have a suitable measurement.
Already own a Levoit purifier? Use our Levoit model-to-filter guide to identify the correct replacement before calculating its recurring cost.
Turn the budget into a buying decision
First eliminate options that do not meet your room requirement. Then price the correct complete filter replacement, choose a plausible replacement frequency, and add your electricity scenario. Compare the remaining models’ purchase prices separately. For a three-year budget, add the purchase price to three years of annualized running costs, while recognizing that actual replacement dates and future prices can differ.
For concrete model tradeoffs, see our Airmega 400 room-size and filter-cost review and Mighty2 versus original Mighty comparison. For a larger-model comparison that includes the Levoit Core 600S-P, see our wildfire-smoke purifier comparison. These guides discuss appliance features and include affiliate links.
Frequently asked questions
Does a lower filter price mean lower ownership cost?
Only after accounting for replacement frequency, the complete filter set, electricity and purchase price. It also needs to be a suitable purifier for the room.
Does a long-life filter mean guaranteed zero spending?
No. Check the model’s stated conditions, cleaning requirements and replacement guidance. A conditional multi-year claim is not a promise that your household will never need a replacement.
Are these measured costs?
No. Filter prices are dated manufacturer references; the annual columns and electricity examples are calculations with stated assumptions. They are intended to help you build your own budget.