# Cubic metre per second

A cubic metre per second (m3s−1, m3/s, cumecs or cubic meter per second in American English) is the unit of volumetric flow rate in the International System of Units (SI) equal to that of a stere or cube with sides of one metre (39.37 in) in length exchanged or moving each second. It is popularly used for water flow, especially in rivers and streams, and fractions for HVAC values measuring air flow.

Cubic metre per second
Unit systemSI
Unit ofvolumetric flow rate
Symbolm3/s
In SI base unitsm3·s−1

The term cumec is also used, as shorthand for "Cubic metres per second",[1] with the plural form cumecs also common in speech.[citation needed] It is commonly used between workers in the measurement of water flow through natural streams and civil works, but rarely used in writing. Data in units of cumec are used along the y-axis or vertical axis of a flow hydrograph, which describes the time variation of discharge of a river (the mean velocity multiplied by cross-sectional area). A moderately sized river discharges in the order of 100 cumecs.

## Conversions

 1 cubic metre per second = 1000 litres per second = 60 kilolitres per minute = 86.4 megalitres per day = 31.5576 gigalitres per year ≈ 219.969 imperial gallons per second ≈ 264.172 US gallons per second ≈ 35.3145 cubic feet per second ≈ 1.305 cubic yards per second ≈ 25566.5 acre-feet per year ≈ 1.11368e+09 cubic feet per year ≈ 0.00757091 cubic miles per year

## References

1. ^ "Units: C", The University of North Carolina at Chapel Hill, webpage: UNC-Rowlett.