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CFM to LPM

1 Cubic Foot per Minute (CFM) = 28.3168Liter per Minute (LPM)

By KAMP Inc. / UnitOwl · Last reviewed:

Result
28.3168 LPM
1 CFM = 28.3168 LPM
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How Many Liters per Minute in a CFM?

One cubic foot per minute (CFM) equals approximately 28.3168 liters per minute (LPM). To convert CFM to LPM, multiply the CFM value by 28.3168. CFM is the standard airflow measurement in American HVAC, compressed air systems, and ventilation engineering. European and international equivalents use LPM, L/s, or m³/h. An HVAC system delivering 400 CFM provides about 11,327 LPM of conditioned air. A portable air compressor rated at 5 CFM delivers about 141.6 LPM. Spray painting booths, clean rooms, laboratory fume hoods, and server room cooling systems all specify airflow in CFM in the US and in LPM or m³/h internationally. The conversion is particularly important for ventilation design, where indoor air quality standards specify minimum airflow per person or per square foot. It is especially useful when US airflow equipment must be matched to international documentation or lab procedures that report gas flow in liters rather than cubic feet. For small blowers, oxygen systems, and bench-scale test rigs, LPM can also be easier to picture than the raw CFM number on a US label.

How to Convert Cubic Foot per Minute to Liter per Minute

  1. Start with your airflow value in CFM.
  2. Multiply the CFM value by 28.3168 to get LPM.
  3. For example, 100 CFM x 28.3168 = 2,831.7 LPM.
  4. For a quick estimate, multiply CFM by 28 (1.1% underestimate).
  5. To convert to m³/h instead: multiply CFM by 1.699 (since 1 CFM = 1.699 m³/h).

Real-World Examples

A bathroom exhaust fan is rated at 80 CFM. Convert to LPM.
80 x 28.3168 = 2,265 LPM. This is adequate for a bathroom up to about 80 sq ft.
A portable air compressor delivers 4.5 CFM at 90 PSI. Express in LPM.
4.5 x 28.3168 = 127.4 LPM. This is enough for most pneumatic nail guns and small spray guns.
An HVAC system provides 1,200 CFM to an open office. Convert to LPM.
1,200 x 28.3168 = 33,980 LPM. ASHRAE recommends about 15-20 CFM per person, so this serves about 60-80 occupants.
A server room requires 200 CFM of cooling airflow per rack. Express in LPM.
200 x 28.3168 = 5,663 LPM per rack. A data center with 50 racks needs about 10,000 CFM (283,168 LPM) total.

Quick Reference

Cubic Foot per Minute (CFM)Liter per Minute (LPM)
128.3168
256.6337
5141.584
10283.168
25707.921
501415.84
1002831.68
50014158.4
1,00028316.8

History of Cubic Foot per Minute and Liter per Minute

CFM became the standard airflow unit in American HVAC engineering because the foot was the base length unit in US construction. Duct sizes are measured in inches, room dimensions in feet, and volumetric airflow naturally followed in cubic feet. ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) established CFM as the standard in their handbooks and standards. International equivalents vary: European HVAC uses m³/h or L/s, Japanese standards use m³/h, and Australian standards use L/s. The conversion to LPM is less common in practice than CFM-to-m³/h or CFM-to-L/s, but LPM is used for smaller-scale applications like medical gas delivery, aquarium air pumps, and laboratory ventilation.

Common Mistakes to Avoid

  • Confusing CFM with cubic feet per hour (CFH). 1 CFM = 60 CFH. Gas appliance ratings (furnaces, water heaters) often use CFH for fuel consumption, while airflow uses CFM. A furnace burning 100 CFH of natural gas is NOT the same as 100 CFM.
  • Applying CFM airflow ratings without accounting for pressure. A compressor rated at "5 CFM at 90 PSI" delivers 5 cubic feet per minute only when the discharge pressure is 90 PSI. At lower pressure, it delivers more CFM; at higher pressure, less.
  • Confusing LPM (liters per minute) with L/s (liters per second). 1 L/s = 60 LPM. In European HVAC, L/s is more common than LPM. Converting CFM to L/s: multiply by 0.4719.
  • Ignoring whether the airflow is standard, actual, or free-air delivery. Gas volume changes with temperature, humidity, altitude, and pressure, so two equal CFM values may not represent the same mass flow.
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Frequently Asked Questions

How do I determine the CFM needed for a room?
For general ventilation: multiply room volume (L x W x H in feet) by the desired air changes per hour (ACH), then divide by 60. A 10x12x8 room (960 ft³) needing 6 ACH: 960 x 6 / 60 = 96 CFM (2,718 LPM). ASHRAE 62.1 provides specific per-person and per-area ventilation rates.
What is SCFM vs CFM?
SCFM (Standard Cubic Feet per Minute) measures airflow at standard conditions (typically 14.696 PSIA, 68°F, 0% humidity). ACFM (Actual CFM) is the flow at actual conditions. At altitude or elevated temperature, ACFM is higher than SCFM for the same mass flow rate. This distinction matters for compressor sizing.
What CFM do common HVAC applications require?
Bathroom exhaust: 50-100 CFM. Kitchen range hood: 100-600 CFM. Residential furnace: 400-2,000 CFM. Commercial air handler: 2,000-50,000 CFM. Hospital operating room: 400-600 CFM with high filtration. Data center per rack: 100-400 CFM.
How many LPM is 100 CFM?
100 CFM equals about 2,831.7 LPM because 100 × 28.3168 = 2,831.68. This is a useful reference point for small ventilation and compressed-air systems.
Why do some ventilation specs use L/s instead of LPM?
L/s lines up more naturally with SI-based engineering equations and produces cleaner numbers for ventilation design. For example, 100 CFM is about 47.2 L/s, which many designers find easier to use than 2,832 LPM in room-by-room schedules.
Quick Tip

CFM to LPM is roughly "multiply by 28" — easy to remember because there are 28.3 liters in a cubic foot. For converting to the more commonly used m³/h in international HVAC: multiply CFM by 1.7. So a 1,000 CFM system is about 1,700 m³/h. These round-number shortcuts cover most estimation needs.

Sources & References