The volumetric flow rate — how much volume passes a point per unit of time.
How it works
The formula Q = V ÷ t relates flow rate, volume, and time; choosing which one to solve for rearranges the same equation around the other two known values.
What this does not include
This does not include mass flow rate, a related but distinct concept that additionally factors in fluid density.
How to use this calculator
- Choose what to solve for, then enter the known values.
A worked example
100 liters flowing over 20 seconds → rate = 100 ÷ 20 = 5 L/s.
Given a rate of 5 L/s and a volume of 100 L, the time works out to 100 ÷ 5 = 20 seconds — the reverse calculation.
What the variables mean
| Variable | Meaning |
|---|---|
| Volume | Total amount of fluid moved |
| Time | Duration over which it flowed |
| Rate | Volume per unit time |
Edge cases worth knowing
A rate of zero makes solving for time impossible — no flow means the volume is never delivered, so there’s no finite time that satisfies the equation.
This calculator solves in either direction — for the rate given volume and time, or for time given volume and rate — rather than being locked to one fixed formula direction.
Frequently asked questions
What’s a practical use for flow rate?
Plumbing and irrigation system design, chemical process engineering, and estimating how long a tank takes to fill or drain at a known rate.
What units does this use?
Liters for volume, seconds for time, and liters per second for the resulting flow rate — adjust as needed for your specific units.
Can flow rate be zero?
Yes — if no volume passes over the given time, the flow rate is correctly reported as zero.
