River Flow Calculator
Estimate discharge in cubic feet per second from stream width, average depth and surface velocity.
Open tool : River Flow CalculatorCFS Converter
Convert cubic feet per second into cubic metres per second, gallons per minute and other flow units.
Enter a value to convert.
Conversion factors
All conversions below are exact arithmetic based on defined unit relationships. Nothing here is an estimate.
| From | To | Multiply by |
|---|---|---|
| 1 cfs | Cubic metres per second | 0.0283168 |
| 1 cfs | Litres per second | 28.3168 |
| 1 cfs | US gallons per minute | 448.831 |
| 1 cfs | Million US gallons per day | 0.646317 |
| 1 cfs | Acre feet per day | 1.98347 |
Reading a flow number
Cubic feet per second is a rate, not a volume. It describes how much water passes a point every second, which is why a gauge reading tells you about right now rather than about the season.
Acre feet per day is the exception in the list above. It is a volume over a full day, so read it as the total that would pass in twenty four hours if the flow held steady.
What a given number means for wading and fishing depends entirely on the river. Four hundred cubic feet per second is high water on a small freestone and barely a trickle on a large tailwater. Learn the numbers for the water you fish rather than looking for a universal threshold.
Common questions
What is a cubic foot per second
One cubic foot of water passing a point every second. It is the standard unit for river discharge in the United States and roughly a basketball sized volume of water per second.
Why convert to other units
Gauges outside the United States report in cubic metres per second, water rights and reservoir figures are often in acre feet, and pump and diversion specs are usually in gallons per minute. Converting lets you compare them directly.
Are these conversions exact
The unit conversions are exact arithmetic. Acre feet per day is a volume over time rather than an instantaneous rate, so read that figure as the total volume that would pass in twenty four hours at a steady flow.