Gallons per Minute to Litres per Minute Converter | GPM to LPM Calculator

💧 Free Online Flow Rate Converter

Gallons per Minute to Litres per Minute Converter

Instantly Convert GPM ↔ LPM — US & Imperial Gallons Supported

Convert gallons per minute to litres per minute (GPM to LPM) or litres per minute to gallons per minute (LPM to GPM) instantly. Supports both US and Imperial gallons with exact formula, reference tables, real-world flow rate examples, and industry presets — free, no sign-up needed.

✅ GPM → LPM

✅ LPM → GPM

✅ US & Imperial Gallons

✅ Industry Presets

Gallons per Minute to Litres per Minute (GPM to LPM)

Gallons per minute (GPM) and litres per minute (LPM) are both units of volumetric flow rate — measuring how much liquid passes a given point per minute. They are used across plumbing, firefighting, irrigation, chemical processing, HVAC, and industrial engineering. This converter handles both directions instantly using the exact SI-defined conversion factors.

🇺🇸 What is GPM (Gallons per Minute)?

Gallons per minute (GPM) is the standard flow rate unit in the United States and is widely used in plumbing, fire protection, and industrial fluid systems. It measures the volume of liquid flowing per minute using the US gallon = 3.785411784 litres (exact). In the UK and older Commonwealth standards, the Imperial gallon = 4.54609 litres is used instead, making Imperial GPM about 20% larger than US GPM.

🌍 What is LPM (Litres per Minute)?

Litres per minute (LPM or L/min) is the metric unit for volumetric flow rate and is the standard in Europe, Australia, Asia, and most of the world. It directly measures how many litres of fluid pass a given point per minute. 1 US GPM = 3.785411784 LPM and 1 Imperial GPM = 4.54609 LPM. LPM is used in medical oxygen delivery, chemical dosing, HVAC cooling, and water treatment.

🔢 The Exact Conversion Factor

The US gallon is defined as exactly 231 cubic inches = 3.785411784 litres, making the GPM-to-LPM conversion exact: 1 US GPM = 3.785411784 LPM. The reverse is 1 LPM = 0.26417205236 US GPM. For Imperial gallons: 1 Imperial GPM = 4.54609 LPM. All conversions on this page use these exact defined values with no rounding in the formula.

💧 Gallons per Minute ↔ Litres per Minute Converter

Choose direction, select gallon type, enter value, and convert instantly

🪣 Gallon Type

🔧 Or Select a Flow Rate Preset

Value in GPM (US GPM)

Result in LPM (L/min)

Converted Value

— L/min

—

Litres/Hour

—

Litres/Second

—

m³/Hour

—

GPM (other gallon)

—

💧 How Gallons per Minute Converts to Litres per Minute — Visual Diagram

🇺🇸 Gallons/Minute

e.g. 10 GPM (US)

🔢 US Factor

3.785411784

🌍 Litres/Minute

37.854 L/min

LPM = GPM (US) × 3.785411784 | LPM = GPM (Imp) × 4.54609 | GPM (US) = LPM × 0.264172

Gallons per Minute to Litres per Minute Formula

The conversion between GPM and LPM is based on the exact definition of the US gallon as 231 cubic inches, which equals exactly 3.785411784 litres. This relationship has been exact since the US adopted the international gallon definition. The Imperial gallon equals 4.54609 litres, giving a slightly different conversion factor for UK flow measurements.

🇺🇸 GPM (US) → LPM Formula

LPM = GPM × 3.785411784

Example: 10 GPM × 3.785411784 = 37.854 L/min

Example: 100 GPM × 3.785411784 = 378.541 L/min

Example: 500 GPM × 3.785411784 = 1,892.706 L/min

🌍 LPM → GPM (US) Formula

GPM = LPM × 0.26417205236 (= LPM ÷ 3.785411784)

Example: 100 LPM × 0.26417 = 26.417 GPM (US)

Example: 1,000 LPM ÷ 3.78541 = 264.172 GPM (US)

🇬🇧 GPM (Imperial) → LPM Formula

LPM = GPM (Imp) × 4.54609

GPM (Imp) = LPM ÷ 4.54609 (= LPM × 0.219969)

Example: 10 GPM (Imp) × 4.54609 = 45.461 L/min

📊 GPM to Other Flow Rate Units

Litres/hour = GPM (US) × 227.1247

Litres/second = GPM (US) × 0.063090

m³/hour = GPM (US) × 0.227125

m³/min = GPM (US) × 0.003785

    💡 Quick Mental Estimate: To quickly convert US GPM to LPM,
    multiply by 3.785 (or roughly 3.8 for a fast
    estimate). To go the other way, multiply LPM by 0.264 (or
    roughly divide by 4 for a quick approximation). These shortcuts
    are accurate to within 0.5% and 6% respectively — useful for rapid field estimates.
  

⚡ Quick Reference — US GPM to LPM

1 GPM3.785 L/min

2 GPM7.571 L/min

5 GPM18.927 L/min

10 GPM37.854 L/min

25 GPM94.635 L/min

50 GPM189.271 L/min

100 GPM378.541 L/min

500 GPM1,892.71 L/min

Gallons per Minute to Litres per Minute Conversion Table

The table below covers GPM values from household taps to large industrial pumps, converted to LPM for both US and Imperial gallons. Values use the exact conversion factors: 1 US GPM = 3.785411784 LPM and 1 Imperial GPM = 4.54609 LPM.

GPM (US)	LPM (L/min)	GPM (Imperial)	LPM (Imperial)	Real-World Context
0.5 GPM	1.893 L/min	0.5 GPM	2.273 L/min	Drinking fountain
1 GPM	3.785 L/min	1 GPM	4.546 L/min	Slow faucet / drip irrigation zone
1.5 GPM	5.678 L/min	1.5 GPM	6.819 L/min	WaterSense low-flow showerhead
2 GPM	7.571 L/min	2 GPM	9.092 L/min	Standard kitchen tap
2.5 GPM	9.464 L/min	2.5 GPM	11.365 L/min	Standard shower head (US max)
5 GPM	18.927 L/min	5 GPM	22.730 L/min	Small sump pump / washing machine
10 GPM	37.854 L/min	10 GPM	45.461 L/min	Garden hose (full flow)
20 GPM	75.708 L/min	20 GPM	90.922 L/min	Small pool pump / lawn irrigation
25 GPM	94.635 L/min	25 GPM	113.652 L/min	Sprinkler system zone
50 GPM	189.271 L/min	50 GPM	227.305 L/min	Medium commercial pump
100 GPM	378.541 L/min	100 GPM	454.609 L/min	Small fire hose / booster pump
250 GPM	946.353 L/min	250 GPM	1,136.52 L/min	Medium fire hose
500 GPM	1,892.71 L/min	500 GPM	2,273.05 L/min	Fire hydrant standard flow
1,000 GPM	3,785.41 L/min	1,000 GPM	4,546.09 L/min	Industrial process pump
5,000 GPM	18,927.1 L/min	5,000 GPM	22,730.5 L/min	Large municipal water pump
10,000 GPM	37,854.1 L/min	10,000 GPM	45,460.9 L/min	Major water main / power plant cooling

Litres per Minute to Gallons per Minute Conversion Table

The reverse table below converts LPM to both US and Imperial GPM. Use this when working with metric-rated pumps, European equipment, or medical flow devices and converting to US or UK gallon-based specifications.

LPM (L/min)	GPM (US)	GPM (Imperial)	L/Hour	Context
1 L/min	0.2642 GPM	0.2200 GPM	60 L/hr	Medical oxygen / IV drip
5 L/min	1.321 GPM	1.100 GPM	300 L/hr	Home water filter
10 L/min	2.642 GPM	2.200 GPM	600 L/hr	Standard shower head (metric)
15 L/min	3.963 GPM	3.300 GPM	900 L/hr	Kitchen tap (full flow)
20 L/min	5.283 GPM	4.399 GPM	1,200 L/hr	Small sump pump
50 L/min	13.209 GPM	10.998 GPM	3,000 L/hr	Medium garden pump
100 L/min	26.417 GPM	21.997 GPM	6,000 L/hr	Pool circulation pump
200 L/min	52.834 GPM	43.994 GPM	12,000 L/hr	Commercial irrigation
500 L/min	132.086 GPM	109.985 GPM	30,000 L/hr	Industrial process pump
1,000 L/min	264.172 GPM	219.969 GPM	60,000 L/hr	Large commercial pump

Where Are GPM to LPM Conversions Used?

Flow rate conversions between gallons per minute and litres per minute are essential across dozens of industries and everyday applications. Here are the most important real-world contexts.

🔧 Plumbing & Water Supply

Plumbers in the US specify pipe sizes, pump capacities, and fixture flow rates in GPM. When working with European or Asian-made fixtures, converting GPM to LPM is routine. A standard US kitchen tap flows at 2.2 GPM (8.33 LPM) and a WaterSense showerhead is limited to 2.0 GPM (7.57 LPM) per US EPA standards. Understanding both units is essential for international fixture selection and compliance.

🚒 Fire Protection & Suppression

Fire hose flows are traditionally specified in GPM in the US, while European and international fire codes use LPM. A standard fire hydrant in the US delivers 500–1,500 GPM (1,893–5,678 LPM). NFPA codes require specific GPM ratings for sprinkler systems, and converting to LPM is essential when specifying internationally sourced pumps, pipes, or sprinkler heads for fire suppression systems.

🌿 Irrigation & Agriculture

Agricultural irrigation systems, drip emitters, and sprinkler zones are rated in both GPM (US) and LPM (rest of world). A typical residential sprinkler zone uses 10–25 GPM (37.9–94.6 LPM). Converting between units is necessary when mixing US-spec irrigation controllers with metric-rated drip tape, emitters, or pumps sourced from European or Australian suppliers.

🏭 Industrial & Chemical Processing

Chemical dosing pumps, heat exchangers, cooling towers, and process pipelines in manufacturing all require precise flow rate specifications. US plants typically use GPM; international plants use LPM or m³/hour. Converting 1,000 GPM = 3,785.41 LPM = 227.1 m³/hr is a critical calculation when specifying international equipment, sizing control valves, or verifying P&ID documentation across borders.

🏊 Pool & HVAC Systems

Swimming pool circulation pumps are rated in GPM in North America and in LPM or m³/h in Europe. A standard 15,000-litre pool needs its water turned over in 6–8 hours — approximately 31–42 LPM (8.2–11 GPM) of continuous pump flow. HVAC chilled water systems similarly mix GPM and LPM specifications when US chillers are paired with European air-handling units.

🏥 Medical & Laboratory

Medical gas supply systems, dialysis machines, and laboratory peristaltic pumps specify flow in LPM worldwide, but some US medical standards still use GPM or cubic feet per minute (CFM). Oxygen concentrators deliver 1–10 LPM (0.26–2.64 GPM). IV infusion pumps and dialysis machines use precise LPM ratings that must be converted when cross-referencing US regulatory documents or comparing device specifications across markets.

✅ US GPM vs Imperial GPM — Key Difference: A pump rated at 100 GPM (US) delivers 378.5 LPM, while a pump rated at 100 GPM (Imperial) delivers 454.6 LPM — a difference of over 20%. Always verify the gallon standard when comparing pump specifications across US and UK equipment sheets. Mixing up gallon types in flow calculations can lead to significantly undersized or oversized pumps, pipes, and valves.

GPM and LPM — Key Facts & Definitions

    📖 Historical Note: The US gallon was standardised at 231 cubic
    inches by the US Congress in 1836, differing from the UK's Imperial gallon
    (defined as 10 pounds of water = 277.42 cubic inches ≈ 4.546 litres) established
    in 1824. Both definitions were later formalised in metric equivalents under the
    international system. The result is two incompatible "gallons" still in use today —
    making GPM-to-LPM conversion essential for global engineering, plumbing, and
    industrial applications.
  

1 US GPM = 3.785411784 LPM (exact, based on US gallon = 231 in³)
1 Imperial GPM = 4.54609 LPM (UK/Ireland/older Commonwealth)
1 LPM = 0.26417205236 US GPM
1 LPM = 0.21996924829 Imperial GPM
Imperial GPM is always approximately 20% larger than US GPM for the same flow
1 US GPM = 60 US gallons/hour = 0.06309 litres/second
1 LPM = 1/60 litres/second = 0.001 m³/min = 0.06 m³/hour
US household tap: typically 1.5–2.5 GPM (5.7–9.5 LPM)
US fire hydrant: typically 500–1,500 GPM (1,893–5,678 LPM)
Standard garden hose: approximately 9–17 GPM (34–64 LPM)

⚠️ Don't Confuse US and Imperial GPM: Equipment datasheets from US manufacturers list GPM in US gallons. UK manufacturers use Imperial gallons. The same pump rated at 100 GPM will show 378.5 LPM (US) vs. 454.6 LPM (Imperial) — a 76-litre-per-minute difference. Always confirm the gallon standard on equipment nameplates, pump curves, and specification sheets before performing flow calculations or pipe sizing.

Frequently Asked Questions — GPM to LPM

How many litres per minute is 1 gallon per minute?

1 US gallon per minute (GPM) = 3.785411784 litres per minute (LPM). This is an exact conversion based on the US gallon being defined as exactly 231 cubic inches = 3.785411784 litres. For Imperial gallons (UK): 1 Imperial GPM = 4.54609 LPM. The converter above handles both gallon types — just select "US" or "Imperial" from the dropdown before converting.

How do I convert GPM to LPM?

To convert US gallons per minute to litres per minute, multiply the GPM value by 3.785411784: LPM = GPM × 3.785411784. Examples: 5 GPM × 3.785 = 18.927 LPM. 50 GPM × 3.785 = 189.27 LPM. 1,000 GPM × 3.785 = 3,785.41 LPM. For Imperial GPM, multiply by 4.54609 instead. Use the converter above for instant results without manual calculation.

How do I convert LPM to GPM?

To convert litres per minute to US gallons per minute, multiply by 0.26417205236 (or divide by 3.785411784): GPM = LPM × 0.26417. Examples: 10 LPM × 0.2642 = 2.642 GPM. 100 LPM × 0.2642 = 26.42 GPM. 500 LPM ÷ 3.785 = 132.09 GPM. For Imperial GPM, divide by 4.54609 instead (LPM × 0.21997).

What is the difference between US GPM and Imperial GPM?

The US gallon = 3.785 litres, while the Imperial (UK) gallon = 4.546 litres — making the Imperial gallon about 20% larger. Therefore, 1 Imperial GPM = 4.546 LPM vs 1 US GPM = 3.785 LPM. A pump rated at 50 GPM (US) delivers 189.3 LPM, but 50 GPM (Imperial) delivers 227.3 LPM. Always check which gallon standard is used in pump curves, equipment specs, and pipe sizing tables before performing calculations.

How many GPM is a standard shower head?

In the US, a standard shower head flows at 2.5 GPM (9.46 LPM) — this is the maximum flow rate under US federal law (42 USC § 6295). WaterSense certified low-flow shower heads must not exceed 2.0 GPM (7.57 LPM). In Europe, typical shower heads flow at 6–12 LPM (1.6–3.2 GPM), with no single regulatory maximum across all EU countries.

How do I convert GPM to m³/hour?

To convert US GPM to cubic metres per hour (m³/hr): multiply by 0.227125. Formula: m³/hr = GPM × 0.227125. Examples: 100 GPM × 0.2271 = 22.71 m³/hr. 1,000 GPM × 0.2271 = 227.1 m³/hr. Alternatively, convert GPM to LPM first (× 3.785), then divide by 1,000 to get m³/min, then multiply by 60 for m³/hr. The result is the same.

What is a good GPM for a well pump?

For a residential home, a well pump should deliver at least 6 GPM (22.7 LPM) to reliably supply normal household demand. Most US residential well pumps are rated 5–25 GPM. For homes with irrigation systems or multiple bathrooms in simultaneous use, 10–15 GPM (37.9–56.8 LPM) is recommended. Commercial properties and farms typically require 50–500+ GPM depending on the application.

Flow Rate Resources & Further Reading

💧 US vs Imperial Gallon

The 20% difference between US and Imperial gallons is one of the most common sources of engineering errors when mixing US and UK specifications. Always confirm gallon type on pump datasheets, fire codes, and plumbing fixtures before converting to LPM for international projects.

Pressure Converters →

🏭 Flow Rate in Industry

Industrial flow rates are expressed in GPM in the US and LPM, m³/hr, or m³/s internationally. Understanding how to convert between these units is essential for pump selection, valve sizing, pipe specification, and process control in global manufacturing and water treatment facilities.

Energy Converters →

🌿 Irrigation Water Use

Agricultural water use is measured in GPM/acre in the US and LPM or m³/ha internationally. Converting GPM to LPM allows farmers and engineers to compare drip tape, sprinkler head, and pump specifications across US and global irrigation equipment suppliers.

Area Converters →