Contact Flow Calculator
A flow rate that looks off, a Reynolds number on the wrong side of the regime line, a pipe internal diameter that disagrees with the manufacturer's table, a feature you wish existed — this page routes your message to the person who can re-run the check and verify your numbers, not a form that vanishes into a queue.
Most replies within two business days — correction reports that affect calculator output are prioritized.
Answered Already, Most Likely
Most flow questions are covered somewhere on the site. These are the destinations that resolve the majority of emails — worth a look before you write. The fastest path to a fixed flow check is usually one of these pages.
Every email read by a humanPhoto: Unsplash- How to Use the Calculator Step by Step
- What Flow Rate Actually Measures
- The Formulas Behind Every Result
- Worked Examples, Numbers and All
- Standard Pipe Sizes & Real Internal Diameters
- Recommended Velocities by Application
- Calculator FAQ on the Home Page
- The Flow Guide Library
What to Include for a Fast Reply
- ✓Browser & device (for UI glitches)
- ✓Your shape and size, fluid preset, temperature and pressure, velocity, and unit system
- ✓The result you expected vs. the result shown
- ✓Page URL or section title if a preset, chart, or guide looks wrong
A screenshot of your calculator inputs halves the back-and-forth.
Pick the Right Inbox
Four routes, four inboxes — each one lands with someone who can act on it. Unsure which fits? Use support@ and we will forward it ourselves.
Flow Support
Calculation & Results Help
A flow rate or pressure drop not matching what you expected? Send the inputs you entered — cross-section shape and size, fluid preset, temperature and pressure, mean velocity, and unit system — along with the result you expected versus the one shown.
Corrections
Report a Formula or Data Error
The engine computes volumetric and mass flow, the Reynolds number and its regime, the Colebrook-White friction factor, Darcy-Weisbach friction loss, pressure drop, pump power, and standard-condition conversions for gases. If any output, pipe dimension, or fluid property disagrees with a published table or your own measurement, send the page URL and exact numbers.
Product Feedback
Feature Requests & Ideas
Want more fluid presets, more pipe standards, saved projects, a printable report, or open-channel and partially-filled-pipe modes alongside the full circular and rectangular sections? We build from what plumbers, HVAC engineers, irrigation designers, and makers actually need at the workbench.
Partners
Partnerships & Trade Education
Fluid property data providers, pipe and pump manufacturers' training teams, trade schools, apprenticeship programs, and HVAC or irrigation associations — we are open to classroom integrations, printed sizing companions, and co-developed calculation tools.
What Happens After You Hit Send
No ticket numbers, no canned macros. Here is the actual path a message takes from your outbox to a verified answer — the same path whether you found a half-percent flow discrepancy or want a new fluid preset.
| Step | What Happens | What It Means for You |
|---|---|---|
| 1 | A Person Reads It | No ticket bot, no autoresponder loop. Messages with exact inputs — shape, diameter, fluid, temperature, velocity — are reproducible, and reproducible messages get answered first. |
| 2 | We Re-Run the Flow Check | For anything numeric, we rebuild your calculation by hand — geometry, hydraulic diameter, fluid properties, Reynolds regime, friction factor, pressure drop, pump power — and compare against the published pipe tables and fluid data before replying. |
| 3 | You Get the Math Attached | The reply shows the formula and the inputs that moved the number. If we were wrong, the reply says so plainly and the fix is dated on the page it affects. |
| 4 | The Receipt Is Kept — Ours, Not Yours | Verified corrections and strong feature requests feed the roadmap. Your email stays with your thread, is never added to a list, and there are no lists to add it to. |
Quick Answers
The five questions we hear most from homeowners, DIYers, and tradespeople.
How do I get a faster reply?▼
Include the exact inputs: the cross-section shape and nominal size or measured internal diameter, the fluid preset and its temperature (plus pressure for gases), the velocity, the unit system, and any constraints you entered. Add the result you expected and the result shown. That one message usually lets us reproduce and explain the difference in a single reply.
Do you offer live chat or phone support?▼
Not yet. Email lets us re-run the full flow calculation and verify every answer against the actual arithmetic and the published pipe and fluid data before responding — which matters when the topic is a pump order or a duct spec. We read every message and answer most within two business days.
Can you tell me which pipe size to use?▼
We can tell you what the calculator's method says for the inputs you enter — and show every formula behind it. But the pipe your system actually needs depends on the material and standard your supplier stocks, the velocity limits your application imposes, and the code your jurisdiction has adopted. Product selection and code compliance belong to your supplier, your engineer, and your local authority.
Do you sell pipe, pumps, or tools?▼
No. The site sells nothing, carries no affiliate links, and is not affiliated with any manufacturer, mill, or distributor. Advertising is clearly labeled and separately handled — see the advertising section of the Privacy Policy for how that works.
Can I suggest a topic for the guide library?▼
Please do — that is how the library grows. Send the question you were trying to answer, the system you were working on, and what you wish had been written down. Requests that describe a real job-site or workbench problem go to the top of the content queue.
Still need a human? One tap away.
One inbox per purpose keeps your message from bouncing between desks.
Everything Links Back to the Tool
Every answer we send names the exact calculator input that changes — shape, diameter, fluid, velocity, or units — so the fix is something you can apply yourself in seconds.