Liters per Minute to CFM: Formula and Examples

Convert liters per minute (L/min) to cubic feet per minute (cfm) by multiplying the flow rate by 0.0353147. Enter a flow rate in L/min to get its equivalent in cfm; the reverse conversion is also straightforward using the reciprocal factor.

Formula

The conversion is: cfm = L/min × 0.0353146667. Here, L/min is the volume of air or another fluid passing a point each minute, and cfm is cubic feet per minute. The factor comes from the exact relationship 1 cubic foot = 28.316846592 liters, so 1 L/min ÷ 28.316846592 = approximately 0.0353146667 cfm.

For the reverse conversion, use L/min = cfm × 28.316846592. The additional calculator output, L/s, is liters per second: L/s = L/min ÷ 60. These are volume-flow units; they describe how much volume moves per unit time, not the speed of the fluid at a particular point.

Worked Example

Using the calculator’s default input of 100 L/min:

1. Convert to cfm: 100 × 0.0353146667 = 3.53146667 cfm.
2. Round to the calculator’s two decimal places: 3.53 cfm.
3. Convert to liters per second: 100 ÷ 60 = 1.6666667 L/s, or 1.67 L/s rounded to two decimal places.

So a flow of 100 L/min is about 3.53 cfm. The rounded cfm figure is suitable for many quick comparisons, but use unrounded values when calculations depend on precision.

What the Units Mean

A liter is a metric unit of volume, while a cubic foot is a US customary and imperial volume unit. “Per minute” in both units makes L/min and cfm directly comparable: each expresses volume passing through a system over one minute. Despite cfm’s frequent use in the United States, the unit is not a measure of mass or weight.

Flow rate is also different from velocity. A duct’s air velocity might be stated in feet per minute (fpm) or meters per second (m/s). To infer volume flow from velocity, you also need the duct’s cross-sectional area; for a uniform flow, volume flow equals average velocity multiplied by area. A cfm value by itself does not specify how quickly air moves at every location in a duct.

Common Conversions and Examples

For a quick estimate, multiply L/min by about 0.0353. For a more precise calculation, use the full factor in the formula. A few examples illustrate the scale:

• 10 L/min ≈ 0.35 cfm.
• 50 L/min ≈ 1.77 cfm.
• 250 L/min ≈ 8.83 cfm.
• 1,000 L/min ≈ 35.31 cfm.

To convert in the opposite direction, multiply cfm by about 28.317. For instance, 5 cfm is approximately 141.6 L/min. Avoid dividing by 0.0353 for this reverse conversion unless you have checked the operation: dividing by that factor and multiplying by its reciprocal are equivalent, but multiplying by 0.0353 again would convert in the wrong direction.

When the Conversion Is Useful

Converting flow units helps when comparing equipment specifications, reading instruments, or matching a measured flow to a requirement expressed in another unit. The arithmetic does not depend on whether the fluid is air, water, or another fluid, provided both figures refer to the same kind of volume-flow measurement under compatible conditions.

For air-moving equipment, a listed cfm rating may be measured under specified conditions or at a particular operating point. A fan’s flow can change with system resistance, such as filters, duct length, bends, and restrictions. Therefore, a direct unit conversion makes two flow values comparable as units, but it does not guarantee that equipment will deliver the converted value once installed.

Reading Specifications and Avoiding Mistakes

Check the exact unit before converting. L/min, L/s, cfm, and cubic feet per hour all describe volume flow, but their time bases differ. Converting L/s as though it were L/min produces a result 60 times too small. Similarly, confusing cubic feet per minute with feet per minute mixes volume flow with velocity.

• Confirm whether the source says L/min or L/s.
• Keep the direction of conversion clear: multiply L/min by 0.0353147 for cfm; multiply cfm by 28.3168 for L/min.
• Round only after doing the calculation, especially when converting back or combining several measurements.
• Check whether a specification refers to actual flow conditions or a standardized reference condition, particularly for gases.

Gas volume can vary with temperature and pressure. A conversion between L/min and cfm changes the volume units but does not correct for different pressure, temperature, humidity, or reference conditions. When comparing gas-flow ratings, check that the measurement basis is consistent; a simple conversion factor alone cannot reconcile different operating conditions.

Frequently Asked Questions

How many cfm is 1 L/min?
One liter per minute is approximately 0.0353147 cfm. For a quick estimate, use 0.0353 cfm.

How do I convert cfm to L/min?
Multiply cfm by 28.316846592. For example, 2 cfm is about 56.63 L/min.

Is L/min the same as L/s?
No. A liter per second is 60 times a liter per minute, so divide L/min by 60 to get L/s.

Are cfm and fpm interchangeable?
No. Cfm measures volume flow per minute; fpm measures distance traveled per minute. To relate them, you also need the flow area and an appropriate average velocity.

Does this conversion account for air pressure or temperature?
No. It converts volume units only. For air or another gas, compare pressure and temperature conditions as well if the figures use different reference conditions.

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in flow | Flow rate | L/min | 100 | 0
out cfm | Flow rate | cfm | flow * 0.0353146667 | 2
out lps | Flow rate | L/s | flow / 60 | 2