Physics and Engineering
Flow Rate Calculator
Flow Rate Calculator calculate volumetric flow from average velocity and circular or rectangular flow area in metric and US customary units.
Physics and Engineering
Flow Rate Calculator
Calculate volumetric flow from average velocity and circular or rectangular flow area in metric and US customary units.
Formula
Volumetric flow rate = cross-sectional area x average flow velocity.
About the Flow Rate Calculator
Calculate volumetric flow from average velocity and circular or rectangular flow area in metric and US customary units.
How the Flow Rate Calculator Works
The selected section area is calculated from diameter or width and height, multiplied by mean velocity, and converted from cubic meters per second to liters and US gallons.
Formula
Volumetric flow rate = cross-sectional area x average flow velocity.
The calculation runs in your browser. Values are validated for required ranges, compatible units, and method-specific restrictions before results are displayed.
Required Inputs
- Flow section shape (required).
- Internal diameter (optional) - enter in m.
- Internal width (optional) - enter in m.
- Internal height (optional) - enter in m.
- Average velocity (required) - enter in m/s.
Results Reported
The result panel reports the final answer and the intermediate quantities needed to check the calculation:
- Cross-sectional area (m2)
- Volumetric flow (m3/s)
- Volumetric flow (L/s)
- Volumetric flow (L/min)
- Volumetric flow (US gal/min)
Flow Rate Calculator Example
Select Example Data in the calculator to load this reproducible input set:
| Input | Example value |
|---|---|
| Flow section shape | circular |
| Internal diameter | 0.1 m |
| Internal width | 0.2 m |
| Internal height | 0.1 m |
| Average velocity | 2 m/s |
How to Use the Calculator
- Confirm that the calculator title and formula match the quantity you need.
- Enter every required value using the unit shown with its field.
- Select Example Data to inspect a valid input set, or enter your own values and select Calculate.
- Review all reported values and the displayed formula before using the answer.
- Use Copy Result or Download CSV when you need a reusable record.
Accuracy and Limitations
Use internal dimensions and cross-section average velocity. Real velocity profiles, partial pipes, compressibility, leakage, fittings, and changing pressure require hydraulic analysis.
Keep units consistent, use measurements that represent the actual situation, retain full precision during the calculation, and round only the final answer. Professional decisions may require current official rules, field measurements, laboratory methods, or specialist review.
Frequently Asked Questions
What does the Flow Rate Calculator calculate?
Calculate volumetric flow from average velocity and circular or rectangular flow area in metric and US customary units.
Which formula does the Flow Rate Calculator use?
Volumetric flow rate = cross-sectional area x average flow velocity. The selected section area is calculated from diameter or width and height, multiplied by mean velocity, and converted from cubic meters per second to liters and US gallons.
What should I check before using the Flow Rate Calculator result?
Use internal dimensions and cross-section average velocity. Real velocity profiles, partial pipes, compressibility, leakage, fittings, and changing pressure require hydraulic analysis.