Why Convert Cubic Feet per Second to Litres per Second?
Engineers, plumbers, and scientists often need to talk about how fast a fluid moves. In the United States, the term cubic foot per second (ft³/s) is common. Across the globe, the metric equivalent is litre per second (L/s). Knowing the exact relationship lets you compare data, size equipment, and avoid costly mistakes.
The Core Conversion Factor
One cubic foot equals exactly 28.3168 litres. Therefore, the conversion rule is simple:
L/s = ft³/s × 28.3168
Understanding the Units
Cubic Foot per Second (ft³/s)
A cubic foot is a cube with each side measuring one foot (0.3048 m). When we say “per second,” we are measuring the volume that passes a point each second. This unit belongs to the Volume Flow Rate measure.
Litre per Second (L/s)
A litre is one‑thousandth of a cubic meter. It is the standard metric unit for small to medium flow rates. Like the cubic foot, “per second” indicates the amount of fluid moving each second.
Step‑by‑Step Worked Example
Imagine a small water pump delivers 3 ft³/s. To find the flow in litres per second:
- Take the conversion factor: 28.3168 L per ft³.
- Multiply: 3 ft³/s × 28.3168 L/ft³ = 84.9504 L/s.
Rounded to a practical precision, the pump moves about 84.95 L/s.
Practical Applications of the Conversion
- HVAC Design: Air handling units are often rated in ft³/s in the U.S., but international standards use L/s. Converting ensures proper sizing of ducts and fans.
- Water Treatment Plants: Flow meters may report in ft³/s, yet dosing chemicals are calculated in L/s.
- Fuel Delivery Systems: Gasoline pumps in some regions use cubic feet per second, while fuel consumption models prefer litres per second.
- Environmental Monitoring: Stream discharge studies frequently need to translate field measurements (ft³/s) into metric reports (L/s) for regulatory compliance.
Cubic Foot Per Second to Litre Per Second Conversion Table
Each row applies the same rule: multiply cubic feet per second by 28.3168.
| Cubic Feet per Second (ft³/s) | Litre per Second (L/s) |
|---|---|
| 1 ft³/s | 28.3168 L/s |
| 2 ft³/s | 56.6336 L/s |
| 5 ft³/s | 141.584 L/s |
| 10 ft³/s | 283.168 L/s |
| 20 ft³/s | 566.336 L/s |
| 50 ft³/s | 1,415.84 L/s |
| 100 ft³/s | 2,831.68 L/s |
| 500 ft³/s | 14,158.4 L/s |
Tips for Accurate Conversions
- Use the factor 28.3168 L/ft³ for most engineering calculations. For high‑precision scientific work, keep the full 28.316846592 L/ft³.
- Maintain consistent units throughout a calculation to avoid hidden errors.
- When rounding, keep at least four significant figures if the downstream process is sensitive.
Key Takeaway
The bridge between the imperial and metric worlds for volume flow rate is a single, reliable factor: 1 ft³/s = 28.3168 L/s. Armed with this number, you can convert instantly, size equipment correctly, and communicate clearly across borders.
Ready to apply the conversion to your next project? Plug the factor into your spreadsheets, calculators, or design software today and see the difference precision makes.