How to Calculate Pipe Flow Rate
What is Pipe Flow Rate?
Pipe Flow Rate Calculator helps contractors and tradespeople accurately size, spec, and estimate materials and systems.
Formula
Q = A × V where A = pipe cross-section area, V = fluid velocity
Step-by-Step Guide
- 1Measure pipe diameter, estimate or measure flow velocity
- 2Apply the formula using your project measurements
- 3Add required safety factors or waste allowances per code
Worked Examples
Input
2 inch pipe (A=0.0218 sf), 5 fps velocity
Result
Q = 0.0218 × 5 = 0.109 cfs = 49 GPM
Common Mistakes to Avoid
- ✕Not applying code-required safety factors or derating
- ✕Forgetting to account for waste and cut losses in material estimates
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