Pipe Flow Rate Calculator
Calculate pipe flow rate in gpm from inside diameter and flow velocity.
1.5 in pipe at 2 ft/s =
11.02 gpm
Representative value from the Pipe Flow Rate Calculator reference table.
Reference Values
Browse 48 reference values with individual detail pages for quick lookup.
Pipe Flow Rate Calculator
Estimate flow from pipe inside diameter and velocity.
Estimated Flow
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Reference Table
Use this complete table for quick lookup and internal linking to specific value pages.
| Scenario | Flow (gpm) | Flow (cfs) | Flow (L/min) |
|---|---|---|---|
| 0.5 in pipe at 2 ft/s | 1.22 gpm | 0.0027 | 4.6 |
| 0.5 in pipe at 3 ft/s | 1.84 gpm | 0.0041 | 7 |
| 0.5 in pipe at 4 ft/s | 2.45 gpm | 0.0055 | 9.3 |
| 0.5 in pipe at 5 ft/s | 3.06 gpm | 0.0068 | 11.6 |
| 0.5 in pipe at 6 ft/s | 3.67 gpm | 0.0082 | 13.9 |
| 0.5 in pipe at 8 ft/s | 4.9 gpm | 0.0109 | 18.5 |
| 0.75 in pipe at 2 ft/s | 2.75 gpm | 0.0061 | 10.4 |
| 0.75 in pipe at 3 ft/s | 4.13 gpm | 0.0092 | 15.6 |
| 0.75 in pipe at 4 ft/s | 5.51 gpm | 0.0123 | 20.9 |
| 0.75 in pipe at 5 ft/s | 6.88 gpm | 0.0153 | 26.1 |
| 0.75 in pipe at 6 ft/s | 8.26 gpm | 0.0184 | 31.3 |
| 0.75 in pipe at 8 ft/s | 11.02 gpm | 0.0245 | 41.7 |
| 1 in pipe at 2 ft/s | 4.9 gpm | 0.0109 | 18.5 |
| 1 in pipe at 3 ft/s | 7.34 gpm | 0.0164 | 27.8 |
| 1 in pipe at 4 ft/s | 9.79 gpm | 0.0218 | 37.1 |
| 1 in pipe at 5 ft/s | 12.24 gpm | 0.0273 | 46.3 |
| 1 in pipe at 6 ft/s | 14.69 gpm | 0.0327 | 55.6 |
| 1 in pipe at 8 ft/s | 19.58 gpm | 0.0436 | 74.1 |
| 1.25 in pipe at 2 ft/s | 7.65 gpm | 0.017 | 29 |
| 1.25 in pipe at 3 ft/s | 11.47 gpm | 0.0256 | 43.4 |
| 1.25 in pipe at 4 ft/s | 15.3 gpm | 0.0341 | 57.9 |
| 1.25 in pipe at 5 ft/s | 19.12 gpm | 0.0426 | 72.4 |
| 1.25 in pipe at 6 ft/s | 22.95 gpm | 0.0511 | 86.9 |
| 1.25 in pipe at 8 ft/s | 30.6 gpm | 0.0682 | 115.8 |
| 1.5 in pipe at 2 ft/s | 11.02 gpm | 0.0245 | 41.7 |
| 1.5 in pipe at 3 ft/s | 16.52 gpm | 0.0368 | 62.6 |
| 1.5 in pipe at 4 ft/s | 22.03 gpm | 0.0491 | 83.4 |
| 1.5 in pipe at 5 ft/s | 27.54 gpm | 0.0614 | 104.3 |
| 1.5 in pipe at 6 ft/s | 33.05 gpm | 0.0736 | 125.1 |
| 1.5 in pipe at 8 ft/s | 44.06 gpm | 0.0982 | 166.8 |
| 2 in pipe at 2 ft/s | 19.58 gpm | 0.0436 | 74.1 |
| 2 in pipe at 3 ft/s | 29.38 gpm | 0.0654 | 111.2 |
| 2 in pipe at 4 ft/s | 39.17 gpm | 0.0873 | 148.3 |
| 2 in pipe at 5 ft/s | 48.96 gpm | 0.1091 | 185.3 |
| 2 in pipe at 6 ft/s | 58.75 gpm | 0.1309 | 222.4 |
| 2 in pipe at 8 ft/s | 78.34 gpm | 0.1745 | 296.5 |
| 3 in pipe at 2 ft/s | 44.06 gpm | 0.0982 | 166.8 |
| 3 in pipe at 3 ft/s | 66.1 gpm | 0.1473 | 250.2 |
| 3 in pipe at 4 ft/s | 88.13 gpm | 0.1963 | 333.6 |
| 3 in pipe at 5 ft/s | 110.16 gpm | 0.2454 | 417 |
| 3 in pipe at 6 ft/s | 132.19 gpm | 0.2945 | 500.4 |
| 3 in pipe at 8 ft/s | 176.26 gpm | 0.3927 | 667.2 |
| 4 in pipe at 2 ft/s | 78.34 gpm | 0.1745 | 296.5 |
| 4 in pipe at 3 ft/s | 117.5 gpm | 0.2618 | 444.8 |
| 4 in pipe at 4 ft/s | 156.67 gpm | 0.3491 | 593.1 |
| 4 in pipe at 5 ft/s | 195.84 gpm | 0.4363 | 741.3 |
| 4 in pipe at 6 ft/s | 235.01 gpm | 0.5236 | 889.6 |
| 4 in pipe at 8 ft/s | 313.34 gpm | 0.6981 | 1,186.1 |
Frequently Asked Questions
Common questions about Pipe Flow Rate Calculator, formulas, and typical use cases.
What formula is used for pipe flow rate?
Flow is calculated as Q = A × v, where A is pipe cross-sectional area and v is flow velocity.
How do you convert cfs to gpm?
Multiply cubic feet per second by 448.831 to get gallons per minute.
Can I use nominal pipe size as inside diameter?
For better accuracy, use actual inside diameter. Nominal size and wall thickness vary by material and schedule.
What velocity range is typical in plumbing systems?
Many domestic systems target moderate velocities to limit noise and pressure loss, often around 2 to 8 ft/s depending on application.
Methodology and Review
This page combines a live calculator, precomputed reference values, and FAQ content from the same conversion definition to reduce mismatch between calculator output and lookup tables.
Editorial metadata (author, reviewer, and update date) is rendered on the page and in structured data. See our editorial policy, review process, and corrections policy.
For compliance-sensitive work, verify final values against project requirements, governing standards, and manufacturer documentation.