Cubic feet per hour (ft³/h) to Litres per second (l/s) conversion

Understanding Cubic feet per hour to Litres per second Conversion

Cubic feet per hour ($ft^3/h$) and litres per second ($l/s$) are both units of volumetric flow rate, which describes how much volume moves through a system over time. Cubic feet per hour is commonly seen in imperial or U.S.-customary contexts, while litres per second is widely used in metric-based engineering, plumbing, ventilation, and scientific applications.

Converting between these units is useful when comparing equipment specifications, interpreting technical documentation from different regions, or standardizing measurements in fluid, air, or gas flow systems. It helps ensure that pumps, ducts, compressors, and pipelines are evaluated using a consistent flow unit.

Conversion Formula

To convert cubic feet per hour to litres per second, use the verified conversion factor:

$$1\ ft^3/h = 0.007865786666337\ l/s$$

So the general formula is:

$$l/s = ft^3/h \times 0.007865786666337$$

For the reverse conversion:

$$1\ l/s = 127.13286571572\ ft^3/h$$

And the reverse formula is:

$$ft^3/h = l/s \times 127.13286571572$$

Step-by-Step Example

Suppose an industrial ventilation system moves air at $850\ ft^3/h$.

Write the formula:

$$l/s = ft^3/h \times 0.007865786666337$$

Substitute the value:

$$l/s = 850 \times 0.007865786666337$$

Calculate:

$$850\ ft^3/h = 6.68591866638645\ l/s$$

So, a flow rate of $850\ ft^3/h$ is equal to $6.68591866638645\ l/s$.

Real-World Examples

• A small laboratory exhaust line rated at $250\ ft^3/h$ can be expressed in litres per second when comparing it with metric ventilation standards.
• A compact aquarium pump delivering $120\ ft^3/h$ may need conversion to $l/s$ for product comparison with internationally listed pumps.
• A building air supply branch carrying $1{,}500\ ft^3/h$ is often converted to litres per second in HVAC design documents used outside the United States.
• A gas handling system moving $3{,}200\ ft^3/h$ may be specified in $l/s$ when equipment components come from metric-based manufacturers.

Interesting Facts

• The cubic foot is a unit based on the foot, which is part of the imperial and U.S. customary measurement systems, while the litre is a metric unit accepted for use with the International System of Units (SI).
  Source: NIST - SI Units: Liter

• Litres per second is a common engineering flow unit because it combines a practical metric volume with a time interval that is easy to interpret in real systems such as water pipes, ventilation ducts, and process lines. Background on volume and litre usage can also be found here:
  Source: Wikipedia - Litre

How to Convert Cubic feet per hour to Litres per second

To convert Cubic feet per hour to Litres per second, multiply the flow rate by the conversion factor from $ft^3/h$ to $l/s$. For $25\ ft^3/h$, this gives a small flow rate in litres per second.

1. Write the given value: Start with the flow rate in Cubic feet per hour.

   $$25\ ft^3/h$$

2. Use the conversion factor: The verified conversion factor is:

   $$1\ ft^3/h = 0.007865786666337\ l/s$$

3. Set up the multiplication: Multiply the given value by the conversion factor so the $ft^3/h$ unit cancels.

   $$25\ ft^3/h \times 0.007865786666337\ \frac{l/s}{ft^3/h}$$

4. Calculate the result: Perform the multiplication.

   $$25 \times 0.007865786666337 = 0.1966446666584$$

5. Result:

   $$25\ \text{Cubic feet per hour} = 0.1966446666584\ \text{Litres per second}$$

A practical tip: if you convert this unit often, keep the factor $0.007865786666337$ handy. Always check that your final unit is $l/s$ after the $ft^3/h$ units cancel.

What is the formula to convert Cubic feet per hour to Litres per second?

Use the verified factor: $1\ \text{ft}^3/\text{h} = 0.007865786666337\ \text{l/s}$.
The formula is $\text{l/s} = \text{ft}^3/\text{h} \times 0.007865786666337$.

How many Litres per second are in 1 Cubic foot per hour?

There are $0.007865786666337\ \text{l/s}$ in $1\ \text{ft}^3/\text{h}$.
This is the standard factor used to convert directly from cubic feet per hour to litres per second.

How do I convert a specific ft3/h value to l/s?

Multiply the flow rate in cubic feet per hour by $0.007865786666337$.
For example, if a device has a flow of $x\ \text{ft}^3/\text{h}$, then its value in litres per second is $x \times 0.007865786666337$.

When is converting ft3/h to l/s useful in real-world applications?

This conversion is useful in HVAC, ventilation, gas flow, and industrial process systems where different regions use different unit standards.
A specification may list flow in $\text{ft}^3/\text{h}$, while engineering calculations or equipment data may require $\text{l/s}$.

Why is the conversion factor so small?

A cubic foot per hour represents a relatively low flow rate when expressed per second, so the value in litres per second is naturally small.
Using the verified factor, each $1\ \text{ft}^3/\text{h}$ equals only $0.007865786666337\ \text{l/s}$.

Can I use this conversion factor for gas and air flow rates?

Yes, if you are only converting the volumetric flow unit from $\text{ft}^3/\text{h}$ to $\text{l/s}$.
The unit conversion factor remains $0.007865786666337$, though pressure, temperature, and gas conditions may still matter in practical engineering work.