GPM to LPM Converter
Convert US gallons per minute to liters per minute for pumps, irrigation, and industrial flow rates.
How It Works
Formula: GPM to LPM = value × 3.785411784
Example: 5 GPM = 18.927059 LPM
Note: 1 US gallon per minute equals 3.7854 liters per minute.
Common Uses
Quick Conversion Table
| GPM | LPM |
|---|---|
| 0.5 | 1.8927 |
| 1 | 3.7854 |
| 2 | 7.5708 |
| 4 | 15.1416 |
| 8 | 30.2833 |
| 16 | 60.5666 |
| 32 | 121.1332 |
| 64 | 242.2664 |
Rounding Rule
Rounded to 4 decimal places
Error Margin
±0.01 LPM
Precision Guidance
For pump specs, round to 2 decimals.
Common Mistakes
Do not confuse US gallons with imperial gallons — a 20% difference.
Frequently Asked Questions
How many liters per minute is 1 GPM?
1 US gallon per minute equals 3.7854 liters per minute (1 US gal = 3.785411784 L).
How do I convert 10 GPM to LPM?
Multiply 10 by 3.7854: 10 GPM = 37.85 LPM.
Is this the US or imperial gallon?
This uses the US gallon (3.785 L). The imperial gallon is 4.546 L.
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Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 US gallon (gal) = 3.785411784 litres (exact, 231 in³)
- EXACT1 US fluid ounce (fl oz) = 29.5735295625 mL (exact, 1/128 gal)
- EXACT1 US cup = 236.5882365 mL (exact, 8 fl oz)
- EXACT1 US pint (pt) = 473.176473 mL (exact, 16 fl oz)
- EXACT1 US quart (qt) = 946.352946 mL (exact, 32 fl oz)
- EXACT1 litre (L) = 1000 millilitres (definition)
Common Pitfalls & How to Avoid Them
US vs. Imperial (UK) cups
A US cup is 236.59 mL, but a UK/metric cup is 250 mL and an Imperial cup is ~284 mL. Recipes from different countries are not interchangeable drop-in.
Fluid ounce is volume, not mass
A US fl oz is 29.57 mL of volume. 1 fl oz of water ≈ 29.57 g, but 1 fl oz of honey or oil weighs more. Do not treat fluid ounces as grams.
Teaspoon/tablespoon sizes differ
1 US tbsp = 14.7868 mL; 1 US tsp = 4.92892 mL. Metric measuring spoons are 15 mL and 5 mL — close but not exact; for baking precision use weighed grams.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
- BIPM (International Bureau of Weights and Measures) — SI Brochure — The International System of Units (9th edition)
Last Updated 2026 | This converter was reviewed for accuracy