Flow Rate Converter
Litres per second, cubic metres per hour, US gallons per minute and cubic feet per minute — the mismatched units that plumbing, HVAC and industrial fluid systems specs use depending on region and industry.
Inputs
Result
3.6 Cubic metre/hour
How it works
- 11 Litre/second → base = 1
- 2Base → Cubic metre/hour = 3.6
How the flow rate converter works
All units convert through litres per second as the base — 1 Litre/minute = 1/60 L/s, 1 Cubic metre/hour = 1/3.6 L/s, 1 Gallon/minute (US) = 0.0630902 L/s, 1 Cubic foot/minute = 0.471947 L/s.
Worked example: 500 US gallons per minute (GPM) to litres per second
- 500 × 0.0630902 ≈ 31.55 L/s.
Common mistakes to avoid
Assuming a US gallon-based flow rate matches a UK-gallon-based one
Since a US gallon and UK (imperial) gallon differ in size, a flow rate specified in 'gallons per minute' needs to specify which gallon convention is meant — mixing them up introduces roughly the same ~20% error the Volume Converter's gallon distinction would.
Confusing flow rate (volume per time) with flow velocity (distance per time)
Flow rate describes how much volume passes a point per unit time; flow velocity describes how fast the fluid itself is moving — these are related (via the Pipe Flow Rate Calculator's area × velocity relationship) but are conceptually and dimensionally distinct quantities.
Frequently asked questions
Why does HVAC and plumbing use so many different flow-rate units?
Different industries and regions developed their own conventional units historically (GPM in US plumbing, m³/h in much of metric-using industry, CFM for airflow specifically) — these conventions have persisted even as cross-regional and cross-industry comparisons increasingly require conversion.
How is this related to the Pipe Flow Rate Calculator?
That tool derives flow rate directly from a pipe's diameter and the fluid's velocity through it; this converter simply translates an already-known flow-rate value between different flow-rate units, regardless of how it was originally derived.
Why is cubic feet per minute (CFM) specifically associated with airflow?
It's the conventional unit for rating fans, HVAC air handling capacity, and ventilation systems in several countries, particularly common in US-based specifications for air-moving equipment.
Does flow rate unit choice affect the actual physical flow, or just how it's described?
Only how it's described — the underlying physical flow is identical regardless of which unit is used to express it; converting between units changes the number, never the real-world flow itself.
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