Ventilation & carbon filter CFM calculator
Fans are rated in free air, but a carbon filter and every duct bend push the fan up its pressure curve where it moves less. Size from the room, then derate for what's bolted to the fan.
Space & restrictions
Result
Room volume 104 ft³
Percentages are rules of thumb, not duct engineering. A speed-controlled fan one size up beats an exact-size fan at full throttle, quieter, and you keep headroom for a clogged filter (they load up over months). Running CO₂ enrichment? Exhausting during lights-on throws that money away.
Sealed room instead of vented? Size the AC → and the CO₂ system →
What size exhaust fan do I need for a grow tent?
Calculate base CFM from your room volume times your target air exchanges per minute, then derate for the static pressure a carbon filter and ducting add, since a filter typically cuts rated CFM by 25-45%. Buying a fan rated at your raw CFM need, with no derating, is the most common undersizing mistake. Enter your room and filter setup above for the CFM to actually shop for.