Calculate stream flow rate, discharge, cubic feet per second, gallons per minute, velocity, cross-sectional area, and water volume over time. Use this stream flow calculator for creeks, streams, ditches, small rivers, irrigation channels, runoff estimates, watershed checks, and outdoor water planning.
Width × depth × velocity:
The calculator estimates cross-sectional area from stream width and average depth, then multiplies by water velocity.
Float method:
Enter float test distance and travel time to estimate surface velocity, then apply a correction factor for average stream velocity.
Known area × velocity:
Enter a measured cross-section area and velocity to calculate flow rate directly.
Volume over time:
Enter a known water volume and time to estimate flow rate, or use calculated flow to estimate total water volume over a duration.
A stream flow calculator helps estimate how much water moves through a creek, stream, ditch, river, or channel over time.
It can be useful for irrigation planning, runoff checks, culvert estimates, watershed planning, pond inflow, stream monitoring, water supply estimates, and nature observations.
Your result shows estimated stream discharge in cubic feet per second, gallons per minute, gallons per day, cubic meters per second, acre-feet per day, total volume over time, velocity, cross-sectional area, and runoff volume estimate.
Multiply the stream cross-sectional area by the average water velocity. If area is in square feet and velocity is in feet per second, the result is cubic feet per second.
CFS means cubic feet per second. It measures how many cubic feet of water pass a point each second.
Measure how long a floating object takes to travel a known distance, then divide distance by time. A correction factor is often applied because surface water can move faster than the average stream flow.
Natural streams have uneven depths, changing velocities, rocks, pools, riffles, vegetation, and irregular banks, so simple field measurements are approximate.