Dial in ventilation for greener, sturdier indoor crops. Switch units, set targets, save results instantly. Know your air changes and upgrade airflow confidently now.
| Unit System | Length | Width | Height | Airflow | Calculated ACH | Required Airflow for 60 ACH |
|---|---|---|---|---|---|---|
| Metric | 3.0 m | 2.4 m | 2.2 m | 950 m³/h | ~59.97 | ~950.40 m³/h |
| Imperial | 10 ft | 8 ft | 7 ft | 560 CFM | ~60.00 | ~560.00 CFM |
Air exchange describes how many times the room’s air is replaced each hour.
Notes: Real airflow may drop due to carbon filters, bends, and duct length. If you measure flow at the exhaust, use that value for best accuracy.
Tip: If temperature swings are large, consider speed control and intake balancing. For strong odor control, prioritize steady negative pressure and sealed leaks.
Healthy plants need steady CO₂ supply, stable humidity, and predictable temperature. Air exchange replaces stale air, removes excess moisture, and reduces fungal pressure. In enclosed tents, it also supports odor control by maintaining mild negative pressure and consistent filtration. Fresh intake air helps keep CO₂ levels from sagging during peak photosynthesis, especially when doors stay closed for long periods.
Target ACH depends on plant density, lighting heat load, and dehumidification strategy. For many small tents, 30–60 ACH is a practical planning range. Higher targets can help with heat spikes, but they may dry plants faster and increase heater or humidifier runtime. Seedlings and clones often prefer gentler air movement, so balance exchange with circulation fans and baffles.
The calculator converts room volume and fan airflow into ACH, or air changes per hour. It also shows minutes per air change, which helps visualize how quickly air is refreshed. If ACH is low, leaf temperature and humidity pockets are more likely, especially under dense canopies. Track readings at canopy height; if humidity remains high after lights off, raising exchange or adding dehumidification can prevent condensation.
Rated fan airflow often drops when you add carbon filters, long ducts, tight bends, backdraft dampers, or restrictive louvers. Consider a safety factor of 15–35% depending on your setup. If you can measure exhaust flow, use measured airflow for the most reliable result. Also consider intake restrictions; passive vents may need larger openings to avoid whistling and pressure losses that reduce fan performance.
Use the required airflow output to meet your target ACH. Match duct diameter to fan size to avoid choking flow, and keep runs short and straight. If odor control is critical, prioritize a sealed enclosure and filter capacity. Recheck values after any layout change. Hot rooms may need cooler intake air.
ACH means air changes per hour. It estimates how many times the room’s total air volume is replaced in one hour based on airflow and volume.
Many small tents plan around 30–60 ACH. Use the lower end for gentle conditions, and increase if heat or humidity rises quickly after lights on or off.
Yes. Filters add resistance and usually reduce real airflow. Enter measured airflow if available, or apply a safety margin so the selected fan still meets your target.
Yes. Restrictive passive intakes can reduce exhaust flow and raise noise. Provide ample intake area or use a powered intake so the exhaust fan can deliver its expected airflow.
Minutes per air change is 60 divided by ACH. It helps you visualize refresh speed. Shorter times generally improve heat and moisture removal, but may increase equipment cycling.
Recalculate after changing duct length, adding bends, swapping filters, or altering room dimensions. Any modification that affects resistance or volume can shift airflow and ACH.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.