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

Understanding Cubic feet per second to Litres per second Conversion

Cubic feet per second ($ft^3/s$) and litres per second ($l/s$) are both units of volume flow rate, which describes how much volume of fluid passes a point in a given amount of time. Cubic feet per second is commonly used in U.S. engineering, hydrology, and water resource reporting, while litres per second is widely used in metric-based technical and scientific contexts.

Converting between these units is useful when comparing flow data from different standards, interpreting pump or pipe specifications, or translating river, drainage, and industrial flow measurements into a preferred measurement system. Because both units measure the same physical quantity, the conversion is a direct multiplication by a fixed factor.

Conversion Formula

To convert cubic feet per second to litres per second, use:

$$l/s = ft^3/s \times 28.316831998815$$

To convert litres per second to cubic feet per second, use:

$$ft^3/s = l/s \times 0.03531468492103$$

These formulas are based on the verified conversion facts:

$$1\ ft^3/s = 28.316831998815\ l/s$$

and

$$1\ l/s = 0.03531468492103\ ft^3/s$$

Step-by-Step Example

Consider a flow rate of $4.8\ ft^3/s$, which could represent water moving through a drainage channel or a medium-sized pipeline.

1. Write the formula

$$l/s = ft^3/s \times 28.316831998815$$

2. Substitute the value

$$l/s = 4.8 \times 28.316831998815$$

3. Calculate

$$l/s = 135.920793594312$$

So:

$$4.8\ ft^3/s = 135.920793594312\ l/s$$

Real-World Examples

• A small stream measured at $2.5\ ft^3/s$ has a flow of $70.7920799970375\ l/s$, useful in hydrology reports that need metric units.
• A stormwater culvert carrying $7.2\ ft^3/s$ corresponds to $203.881190391468\ l/s$, a scale relevant in municipal drainage design.
• An irrigation channel with a discharge of $0.9\ ft^3/s$ equals $25.4851487989335\ l/s$, which can be helpful when comparing pump output to field water demand.
• A water transfer line operating at $15\ ft^3/s$ delivers $424.752479982225\ l/s$, a substantial flow rate often seen in utility or treatment infrastructure.

Interesting Facts

• The cubic foot is a customary unit derived from the foot, while the litre is a metric unit equal to one cubic decimetre. This makes conversions between $ft^3/s$ and $l/s$ especially common when data moves between U.S. customary and SI-related systems. Source: NIST - SI Units
• Cubic feet per second, often abbreviated as "cfs," is widely used in river and stream discharge reporting by U.S. agencies such as the U.S. Geological Survey. Source: USGS Water Science School

How to Convert Cubic feet per second to Litres per second

To convert Cubic feet per second to Litres per second, multiply the flow rate by the conversion factor between the two units. For this example, use the verified factor $1\ \text{ft}^3/\text{s} = 28.316831998815\ \text{l/s}$.

1. Write the conversion formula:
   Use the standard volume flow rate formula:

   $$\text{Litres per second} = \text{Cubic feet per second} \times 28.316831998815$$

2. Substitute the given value:
   Insert $25\ \text{ft}^3/\text{s}$ into the formula:

   $$\text{l/s} = 25 \times 28.316831998815$$

3. Multiply the values:
   Perform the calculation:

   $$25 \times 28.316831998815 = 707.92079997036$$

4. Result:

   $$25\ \text{ft}^3/\text{s} = 707.92079997036\ \text{l/s}$$

A quick way to check your work is to estimate: $25 \times 28.3 \approx 707.5$, which is very close to the exact result. For precise engineering or fluid calculations, always use the full conversion factor.

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

To convert Cubic feet per second to Litres per second, multiply the flow rate in ft$^3$/s by the verified factor $28.316831998815$. The formula is $l/s = ft^3/s \times 28.316831998815$. This gives the equivalent volumetric flow rate in metric units.

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

There are exactly $28.316831998815$ Litres per second in $1$ ft$^3$/s. This is the verified conversion factor used for all calculations on the page. It is useful as a quick reference point for larger conversions.

Why would I convert ft$^3$/s to l/s in real-world applications?

This conversion is common in hydrology, water treatment, irrigation, and pump system design. In many countries, flow rates are reported in $l/s$, while some engineering data or older systems may use ft$^3$/s. Converting between them helps compare measurements and ensure consistency in reports and specifications.

Can I convert decimal values of Cubic feet per second to Litres per second?

Yes, the same conversion factor applies to whole numbers and decimals. Multiply any value in ft$^3$/s by $28.316831998815$ to get the result in $l/s$. For example, $0.5$ ft$^3$/s would be converted using the same formula.

Is ft$^3$/s a volume or a flow rate unit?

ft$^3$/s is a volumetric flow rate unit, not just a unit of volume. It describes how many cubic feet of fluid pass a point each second. The equivalent metric flow rate can be expressed in $l/s$ using $1$ ft$^3$/s $= 28.316831998815$ l/s.

Do I need to round the result when converting ft$^3$/s to l/s?

You can round the result depending on the level of precision needed for your application. For everyday use, a few decimal places may be enough, while technical work may require more. The exact verified factor is $28.316831998815$, so rounding should be done only after the conversion.