Gallons per Second
0
Equivalent flow rate
Accurate conversion between L/s and gal/s for civil engineering, hydrology, water treatment and industrial flow
Convert litres per second to gallons per second instantly with precise calculations. Supports both US and Imperial gallons. Includes reverse conversion, full formula reference, real-world flow rate examples, and comprehensive comparison tables for 2026.
Professional flow rate conversion for civil engineering, water treatment, hydrology, fire suppression, and large-scale industrial systems
Convert litres per second to gallons per second using exact internationally defined factors: 1 US gallon = 3.785411784 litres and 1 Imperial gallon = 4.54609 litres exactly. Our tool outputs results in both US gallons per second and Imperial gallons per second simultaneously, along with cubic metres per second, cubic feet per second, and litres per minute, giving you a complete multi-unit flow rate breakdown in one step for 2026.
The US gallon and the Imperial (UK) gallon are fundamentally different units — a distinction that is critical in high-volume flow rate calculations. The US gallon is exactly 3.785411784 litres while the Imperial gallon is exactly 4.54609 litres, a difference of approximately 20%. Our converter clearly distinguishes both so you can use the correct value whether you are working with a US hydraulic design standard or a legacy UK water authority specification.
Litres per second (L/s) is the standard flow rate unit used in civil and hydraulic engineering, water supply design, wastewater treatment, and hydrology across Australia, Europe, and most of the world. Gallons per second (gal/s) is used primarily in the United States for high-volume hydraulic and fire suppression engineering. Accurate conversion between L/s and gal/s is essential when specifying pumps, pipes, treatment plant capacity, and dam spillway discharge across metric and US customary systems in 2026.
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Litres per second (L/s) is a metric unit of volumetric flow rate measuring the volume of fluid passing a reference point per second, expressed in litres. It is the standard high-volume flow rate unit used in civil engineering, water supply infrastructure, river hydrology, wastewater treatment, and large pump station design across Australia, Europe, and most of the world. One litre per second equals 3.6 cubic metres per hour and 60 litres per minute, making it a convenient unit that bridges the gap between the very large m³/s (used for rivers and dam discharges) and the smaller L/min (used for household and small commercial flows).
Gallons per second (gal/s) is the US customary and Imperial equivalent, used primarily in North American hydraulic engineering, fire suppression system design, and large industrial flow specifications. As with all gallon-based conversions, a critical distinction must be made between the US gallon (3.785411784 litres exactly) and the Imperial gallon (4.54609 litres exactly) — a 20% difference that is highly significant at the large flow rates where L/s and gal/s are typically used. For related conversions, see the pressure converter for pump and hydraulic system design.
1 L/s = 0.264172 US gal/s and 1 L/s = 0.219969 Imperial gal/s. At large industrial or civil engineering flow rates, this 20% difference between US and Imperial gallons becomes highly significant — always confirm which gallon system is used in any specification, standard, or equipment datasheet before applying the conversion.
The conversion between litres per second and gallons per second uses the exact internationally defined volume of each gallon. Because both the US gallon and Imperial gallon are defined in terms of litres with exact decimal values, the conversion factors carry no inherent rounding error in their base definitions.
Example 1: 100 L/s ÷ 3.785411784 = 26.417 US gal/s
Example 2: 100 L/s ÷ 4.54609 = 21.997 Imp gal/s
Example 3: 50 US gal/s × 3.785411784 = 189.271 L/s
Bar heights are proportional to illustrate relative flow rate values — US gal/s shown
Use this quick-reference table to look up common litres per second to gallons per second conversions. Values are shown for both US and Imperial gallons using exact conversion factors. For values not shown, use the calculator above.
| Litres/sec (L/s) | US Gal/s | Imp Gal/s | m³/s | ft³/s (cusec) |
|---|---|---|---|---|
| 0.1 L/s | 0.02642 US gal/s | 0.02200 Imp gal/s | 0.0001 m³/s | 0.003531 ft³/s |
| 0.5 L/s | 0.13209 US gal/s | 0.10998 Imp gal/s | 0.0005 m³/s | 0.017657 ft³/s |
| 1 L/s | 0.26417 US gal/s | 0.21997 Imp gal/s | 0.001 m³/s | 0.035315 ft³/s |
| 5 L/s | 1.32086 US gal/s | 1.09985 Imp gal/s | 0.005 m³/s | 0.17657 ft³/s |
| 10 L/s | 2.64172 US gal/s | 2.19969 Imp gal/s | 0.010 m³/s | 0.35315 ft³/s |
| 25 L/s | 6.60430 US gal/s | 5.49923 Imp gal/s | 0.025 m³/s | 0.88287 ft³/s |
| 50 L/s | 13.2086 US gal/s | 10.9985 Imp gal/s | 0.050 m³/s | 1.76573 ft³/s |
| 100 L/s | 26.4172 US gal/s | 21.9969 Imp gal/s | 0.100 m³/s | 3.53147 ft³/s |
| 250 L/s | 66.0430 US gal/s | 54.9923 Imp gal/s | 0.250 m³/s | 8.82867 ft³/s |
| 500 L/s | 132.086 US gal/s | 109.985 Imp gal/s | 0.500 m³/s | 17.6573 ft³/s |
| 1,000 L/s | 264.172 US gal/s | 219.969 Imp gal/s | 1.000 m³/s | 35.3147 ft³/s |
| 5,000 L/s | 1,320.86 US gal/s | 1,099.85 Imp gal/s | 5.000 m³/s | 176.573 ft³/s |
Litres per second and gallons per second are used for high-volume flow rates in engineering and infrastructure. The following examples relate these units to familiar real-world systems encountered in civil and industrial engineering in 2026.
A typical residential water main supplying a suburb delivers approximately 50–200 L/s, equal to 13.2–52.8 US gal/s. Individual household connections draw around 0.1–0.3 L/s (0.026–0.079 US gal/s) at peak demand. Water utilities in Australia and Europe design supply systems in L/s while US water authorities use US gal/s — making accurate conversion essential for international infrastructure projects and equipment procurement in 2026.
Commercial fire sprinkler systems are designed to deliver flow rates of 1–10 L/s (0.264–2.642 US gal/s) depending on hazard classification. Large fire hydrant systems for industrial facilities may require 30–100 L/s (7.9–26.4 US gal/s). US fire engineering standards (NFPA) specify flows in US gal/s or US gal/min, while Australian and European standards (AS, EN) use L/s — making this one of the most common L/s to gal/s conversion needs in building services engineering.
Small urban creeks during heavy rain may flow at 5–50 L/s (1.32–13.2 US gal/s). Major rivers can discharge thousands of cubic metres per second — the Murray River in Australia has a mean discharge of approximately 767 m³/s = 767,000 L/s (202,629 US gal/s). Hydrologists and civil engineers use L/s for small catchment and drainage design, converting to and from US gal/s when comparing with North American hydrology data or international flood modelling standards.
A small regional water treatment plant may process 100–500 L/s (26.4–132.1 US gal/s). A large metropolitan treatment plant serving a major city processes 2,000–10,000 L/s (528–2,642 US gal/s). Treatment plant capacity is universally specified in L/s in Australia, while US equivalents use millions of gallons per day (MGD) or US gal/s. Converting between these systems is essential for comparing international treatment technologies and equipment procurement.
Heavy-duty centrifugal pumps used in mining dewatering, process plants, and large irrigation schemes can deliver 500–5,000 L/s (132–1,321 US gal/s). Pump manufacturers publish performance curves in L/s for metric markets and US gal/s for North American markets. Hydraulic engineers must accurately convert these figures when selecting pumps from global suppliers or adapting US-designed pump stations for installation in Australian or European infrastructure projects.
An Olympic swimming pool holds 2,500,000 litres (2,500 m³). A typical pool fill rate from a large commercial supply connection of 10 L/s (2.642 US gal/s) would take approximately 69 hours (nearly 3 days) to fill. At a fire hydrant supply rate of 60 L/s (15.85 US gal/s) the same pool fills in about 11.6 hours. This example illustrates how L/s values translate to real-world volumes over time and why accurate L/s to gal/s conversion matters in water infrastructure planning.
The L/s and gal/s units coexist in civil engineering, hydraulics, water management, and fire safety across the world. While most countries have adopted SI units and specify high-volume flow rates in L/s or m³/s, the United States continues to use US gal/s and US gal/min in hydraulic engineering, fire safety codes (NFPA), and water utility reporting. Anyone working across these jurisdictions regularly needs accurate L/s to gal/s conversion.
Our L/s to gal/s converter delivers instant, accurate results on any device. Follow these simple steps to convert your flow rate value in seconds.
The National Institute of Standards and Technology provides the official US gallon definition (3.785411784 L) and other volume units used as the reference standard for this converter and all official US engineering calculations.
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