Start here · plan a quiet DIY air purifier

How much purifier does your room need?

Answer three questions. You'll get the clean air your room needs, and how three proven DIY designs would get you there: how many to build, how fast to run them, roughly what they cost.

1 · Your room

2 · How clean

3 · How quiet

—
of clean air (CFM) your room needs

Three ways to get there

Clean air for the PC-fan boxes = airflow × the share of fine particles a filter catches in one pass (we assume 60% for MERV 13, 45% for MERV 11, an estimate). The CR box uses whole-box clean-air measurements from published tests. Noise for the PC-fan boxes is lab-scale (Cybenetics chamber); CR box noise is as each tester measured it, so the two aren't on the same scale. Costs cover fans and one set of filters; wiring and wood are extra.

Compared with a store-bought purifier and a kit

Next steps

Pick a filter

The Filters page ranks every filter we have test data for by the airflow it leaves your fans.

Pick fans and speeds

The Fans page shows lab curves and the PWM % to set for each noise level.

See real builds

Builds shows the boxes we've made, what's in them and how they're doing.