The short answer
Yearly cost = (filter price × replacements per year) + (average watts × hours × electricity rate). For many units, filters cost more than the electricity.
The formula
Replacements per year = 12 ÷ the maker's interval in months. Electricity per year = average watts × 24 × 365 ÷ 1,000 × your rate per kWh. Use the average draw on the setting you actually use, not the maximum.
Example
| Item | Assumption | Per year |
|---|---|---|
| HEPA filter | One every 6 months | 2 filters |
| Carbon filter | One every 3 months | 4 filters |
| Electricity | 25 W average, 16¢/kWh | about $35 |
Check the current filter price on each product page; it changes often.
Ways to save
- Vacuum the pre-filter regularly so the main filter lasts.
- Size the unit so it runs on low.
- Use auto mode.
- Buy filter multipacks when the maker sells them.
Products mentioned
Questions readers ask
Do purifier filters cost more than electricity?
For many units, yes; compare filter prices before buying.
Can I wash a HEPA filter to save money?
Only if the maker says it's washable; washing standard HEPA damages it.