Flow Rate Calculator

Flow is the answer to most servicing questions: what can this pipe deliver, what is that pump pushing, what does this house actually use. Two honest ways to find it - the math from pipe and velocity, and the bucket test that trusts nothing.

Flow Rate Calculator does both, in whatever units you keep on site.

• Two methods: Pipe & velocity math, or a real bucket-timer test.
• Instant outputs: GPM, LPM, GPH, L/s and m3/h.
• Any units: Inches, mm, fps, m/s, gallons and litres.
• Field ready: Bucket sizes built in.
• Live update: Results recompute as you type.
• Export: Text, CSV or JSON report.

1. Pick a method: from pipe & velocity, or bucket test.
2. For the pipe method, enter the internal bore and water velocity.
3. For the test method, enter the container volume and the time it took to fill.
4. Read the flow in GPM or LPM on the hero card.
5. Export the result for the record.

Example 1 — Pipe flow. A 3/4 in (0.785 in bore) pipe at 4 fps carries about 6.0 GPM.

Example 2 — Bucket test. A 5 L bucket fills in 12 s: flow = 25 LPM.

Example 3 — Metric pipe. A 20 mm bore at 1.2 m/s moves ~22.6 LPM.

• Two verified methods: Math plus a physical test.
• Field practical: Built-in bucket sizes.
• Every unit: All common flow measures.
• No installs: Works offline in a browser.
• Free and private: No uploads, no logging.