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 (cusec), and litres per minute — a complete multi-unit breakdown in one step for 2026.
The US gallon (3.785411784 L) and the Imperial gallon (4.54609 L) differ by approximately 20% — a critical distinction at the large flow rates where L/s and gal/s are typically used. A 20% sizing error on a major pump station or water treatment plant can represent millions of dollars in over- or under-capacity. Our converter clearly outputs both gallon types simultaneously so engineers can select the correct value for each application.
Litres per second is the standard high-volume flow rate unit in civil and hydraulic engineering, water supply, wastewater treatment, and hydrology in Australia, Europe, and most of the world. Gallons per second is used primarily in the United States for hydraulic engineering, fire suppression (NFPA standards), and large industrial flow. Accurate L/s to gal/s conversion is essential for international pump procurement, cross-border infrastructure projects, and comparing technical specifications 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 each second, expressed in litres. It is the standard high-volume flow rate unit used across civil engineering, water supply infrastructure, wastewater treatment, river hydrology, and large pump station design in 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 practical unit that bridges 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 (NFPA standards), and large industrial flow specifications. The critical distinction between the US gallon (3.785411784 litres exactly) and the Imperial gallon (4.54609 litres exactly) — a 20% difference — is highly significant at the large flow rates where L/s and gal/s are typically applied. Always confirm which gallon system is used in any engineering specification before converting. For pump and hydraulic system design, see also the pressure converter.
1 L/s = 0.264172 US gal/s and 1 L/s = 0.219969 Imperial gal/s. At large civil engineering flow rates the 20% gap between US and Imperial gallons is highly consequential — always confirm the gallon system used in any specification, standard, or equipment datasheet before applying a conversion factor.
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 custom values, use the calculator above.
| Litres/sec (L/s) | US Gal/s | Imp Gal/s | m³/s | ft³/s (cusec) |
|---|---|---|---|---|
| 0.1 L/s | 0.026417 US gal/s | 0.021997 Imp gal/s | 0.0001 m³/s | 0.003531 ft³/s |
| 0.5 L/s | 0.132086 US gal/s | 0.109985 Imp gal/s | 0.0005 m³/s | 0.017657 ft³/s |
| 1 L/s | 0.264172 US gal/s | 0.219969 Imp gal/s | 0.001 m³/s | 0.035315 ft³/s |
| 5 L/s | 1.320860 US gal/s | 1.099846 Imp gal/s | 0.005 m³/s | 0.176573 ft³/s |
| 10 L/s | 2.641721 US gal/s | 2.199692 Imp gal/s | 0.010 m³/s | 0.353147 ft³/s |
| 25 L/s | 6.604301 US gal/s | 5.499231 Imp gal/s | 0.025 m³/s | 0.882867 ft³/s |
| 50 L/s | 13.20860 US gal/s | 10.99846 Imp gal/s | 0.050 m³/s | 1.765735 ft³/s |
| 100 L/s | 26.41721 US gal/s | 21.99692 Imp gal/s | 0.100 m³/s | 3.531470 ft³/s |
| 250 L/s | 66.04301 US gal/s | 54.99231 Imp gal/s | 0.250 m³/s | 8.828675 ft³/s |
| 500 L/s | 132.0860 US gal/s | 109.9846 Imp gal/s | 0.500 m³/s | 17.65735 ft³/s |
| 1,000 L/s | 264.1721 US gal/s | 219.9692 Imp gal/s | 1.000 m³/s | 35.31470 ft³/s |
| 5,000 L/s | 1,320.860 US gal/s | 1,099.846 Imp gal/s | 5.000 m³/s | 176.5735 ft³/s |
Litres per second and gallons per second are used for high-volume flow rates in engineering and infrastructure. The following examples connect these units to familiar real-world systems and projects encountered in civil and industrial engineering in 2026.
A typical residential suburb water main 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 global pump procurement in 2026.
Commercial fire sprinkler systems deliver 1–10 L/s (0.264–2.642 US gal/s) depending on hazard classification. Large industrial hydrant systems may require 30–100 L/s (7.9–26.4 US gal/s). US fire engineering standards (NFPA) specify flows in US gal/min and US gal/s, while Australian and European standards (AS, EN) use L/s — making L/s to gal/s conversion one of the most common needs in international building services engineering.
Small urban drains during heavy rain flow at 5–50 L/s (1.32–13.2 US gal/s). Major rivers carry far higher flows — the Amazon River discharges approximately 209,000 m³/s = 209,000,000 L/s (55.2 million US gal/s). Hydrologists 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 processes 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). Australian plant capacity is specified in L/s while US equivalents use millions of gallons per day (MGD). Converting between these systems is critical for comparing international treatment technologies and procuring globally sourced equipment.
Heavy-duty centrifugal pumps used in mining dewatering, process plants, and large irrigation schemes 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 to Australian or European infrastructure specifications.
An Olympic swimming pool holds 2,500,000 litres (2,500 m³). A commercial supply connection delivering 10 L/s (2.642 US gal/s) fills the pool in approximately 69 hours. At a fire hydrant rate of 60 L/s (15.85 US gal/s) the same pool fills in about 11.6 hours. This illustrates how L/s values relate to real-world volumes over time — a critical consideration in water infrastructure planning, emergency response, and tank sizing calculations.
The L/s and gal/s units coexist in civil engineering, hydraulics, water management, and fire safety worldwide. While most countries specify high-volume flow rates in L/s or m³/s under SI, the United States continues to use US gal/s and US gal/min in hydraulic engineering, NFPA fire safety codes, and water utility reporting. Anyone working internationally 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 in seconds.
The National Institute of Standards and Technology defines the US gallon as exactly 3.785411784 litres — the reference standard used for this converter and all official US engineering calculations involving volume and flow rate.
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