Flow Rate Converter

Convert flow rate — L/s, L/min, m³/h, GPM (US & UK), CFM.

100% Browser-Based • Local Processing

How this conversion works

The relation

Worked example
    4

    Common flow rate conversions

    L/minUS GPM
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    Overview

    What is a Flow Rate Converter?

    > Flow Rate Converter converts volumetric flow between L/s, L/min, m³/h, gallons per minute (US and UK), and CFM. Enter a value, pick your units, and read the result with the exact factor shown (1 US GPM = 3.785 L/min; 1 m³/h = 16.667 L/min). US and UK GPM differ. Works offline. ---

    ### H2: Convert flow rate — pump, water, and air units

    Flow rate is the volume of fluid passing a point per unit of time, and it's measured in a range of units across plumbing, pumps, and HVAC. Metric work uses litres per second (L/s), litres per minute (L/min), and cubic metres per hour (m³/h); water and pump specs often use gallons per minute (GPM); and air systems use cubic feet per minute (CFM). This converter handles all of them, so a pump rated in GPM becomes L/min, or an HVAC airflow in CFM becomes m³/h, in one step. Every result shows the exact factor, with a swap button and an all-units table.

    The trap to watch — the same one that bites with volume — is that a US gallon is not a UK gallon. A US gallon is 3.785 litres; the imperial (UK) gallon is 4.546 litres, about 20% bigger. So "10 GPM" means a noticeably larger flow in the UK than in the US. This tool keeps US GPM and UK GPM as separate, labelled units so you never mix them up. One US GPM is 3.785 L/min; one UK GPM is 4.546 L/min.

    The other useful metric relationships: one cubic metre per hour is 16.667 L/min (or 0.2778 L/s), and one L/s is 3.6 m³/h. For air, one CFM is about 28.317 L/min, or 1.699 m³/h — handy for sizing fans and compressors.

    One honest distinction: this converts volumetric flow (volume per time), not mass flow (mass per time, like kg/s). Mass flow depends on the fluid's density, so converting between the two needs the density of the specific fluid — that's a separate calculation. For plain volume amounts (not per time), use the Volume Converter. Everything runs on your own device, offline, with nothing uploaded.

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    Guide

    How to use the Flow Rate Converter

    Step 1: Enter your value. Type the flow rate you want to convert into the input box

    Decimals are fine.

    Step 2: Pick the "from" unit. Choose your starting unit — and if it's GPM, make sure you've selected US or UK

    Pick the "from" unit. Choose your starting unit — and if it's GPM, make sure you've selected US or UK.

    Step 3: Pick the "to" unit. Choose the unit you want the answer in — again minding US vs UK

    The result updates instantly.

    Step 4: Read the result and the factor. The converted value appears with the exact relationship used (for example, 1 US GPM = 3.785 L/min), so you can verify it

    Read the result and the factor. The converted value appears with the exact relationship used (for example, 1 US GPM = 3.785 L/min), so you can verify it.

    Step 5: Copy, swap, or expand. Use Copy to grab the number, the swap button to reverse the direction, or open the all-units table to see your value in every unit at once

    Adjust the decimal places for more precision.

    Screens

    Flow Rate Converter in action

    Flow rate converter turning 20 litres per minute into 5.2834 US gallons per minute, with the note underneath reading that one US gallon per minute is exactly 3.785411784 litres per minute.
    Converting litres per minute to US gallons per minute, with the exact factor underneath
    The flow rate converter unit list open at the boundary between its metric group and its US group, with US gallon per minute below the heading and the imperial gallon and cubic foot per minute entries under that.
    The unit list, grouped and searchable
    The litres per minute to US gallons per minute reference table listing pump rates from 1 L/min to 200 L/min beside their US gallon per minute readings.
    The reference table for the pair on screen
    The flow rate converter on a phone screen, the two panes stacked with the swap control between them.
    The same tool on a phone
    Support

    Frequently Asked Questions

    How many L/min are in a GPM?

    It depends on the gallon. One US GPM is 3.785 litres per minute; one UK (imperial) GPM is 4.546 L/min — about 20% more, because a UK gallon is larger. So "10 GPM" is 37.85 L/min in the US but 45.46 L/min in the UK. The tool labels both and shows the factor with every result.

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    Is GPM US or UK gallons?

    It can be either, which is exactly why you have to check. In the US, GPM uses the US gallon (3.785 L); in the UK, it uses the imperial gallon (4.546 L). The same "GPM" number therefore means a bigger flow in the UK. This tool keeps US GPM and UK GPM as separate, labelled units so you don't accidentally use the wrong one.

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    How do I convert GPM to L/min and back?

    Multiply US GPM by 3.785 to get L/min (or by 4.546 for UK GPM). To reverse it, divide L/min by 3.785 for US GPM. For example, 15 US GPM × 3.785 = 56.8 L/min, and 100 L/min ÷ 3.785 = 26.4 US GPM. The tool applies the exact factor for whichever gallon you choose and shows it.

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    How many m³/h is 1 L/s?

    Exactly 3.6 cubic metres per hour. Since one cubic metre is 1000 litres and an hour is 3600 seconds, 1 L/s = 1000 × 3600 ÷ 1000 = 3.6 m³/h. So 5 L/s is 18 m³/h. To reverse it, divide m³/h by 3.6 to get L/s. It's a clean metric conversion, and the tool shows the factor.

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    How do I convert m³/h to GPM?

    Multiply cubic metres per hour by 4.403 to get US GPM (or by 3.666 for UK GPM). This comes from 1 m³/h = 16.667 L/min ÷ 3.785 L per US gallon. So a pump at 10 m³/h delivers about 44 US GPM. The tool converts m³/h to either GPM standard, with the exact factor and gallon type shown.

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    What is CFM, and how do I convert it?

    CFM is cubic feet per minute, a volumetric flow unit used for air in HVAC, fans, and compressors. One CFM is about 28.317 litres per minute, or 1.699 m³/h, since a cubic foot is 28.317 litres. So a 400 CFM fan moves roughly 680 m³/h. The tool converts CFM to any of the metric or gallon-based flow units.

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    What's the difference between US GPM and UK GPM?

    Just the gallon. A US gallon is 3.785 litres and an imperial (UK) gallon is 4.546 litres — about 20% bigger — so a UK GPM represents a larger flow than a US GPM. A "50 GPM" pump is 189 L/min if US, but 227 L/min if UK. Because they share the name, always confirm which gallon a spec uses; the tool separates them.

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    Is this volumetric flow or mass flow?

    Volumetric. This tool converts volume per time — litres, cubic metres, gallons, or cubic feet, each per unit of time. Mass flow (like kilograms per second) is different: it measures how much *mass* passes per time, which depends on the fluid's density. Converting between volumetric and mass flow needs the specific fluid's density, so it's a separate calculation this tool doesn't do.

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    How do I convert L/s to L/min and m³/h?

    Multiply L/s by 60 to get L/min, and by 3.6 to get m³/h. So 2 L/s is 120 L/min or 7.2 m³/h. To go back, divide L/min by 60 or m³/h by 3.6 to return to L/s. These are exact metric relationships based on 60 seconds per minute and 3600 seconds per hour, and the tool shows the factor used.

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    Is this converter exact, or does it round the answer?

    The math is exact — it uses defined factors (US gallon = 3.785412 L, UK gallon = 4.54609 L, cubic foot = 28.31685 L). Only the *displayed* value is rounded for readability, and you can add decimal places for more precision. The factor and gallon system shown with each result let you verify the figure yourself.

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    What's the formula to convert flow-rate units?

    Convert everything through litres per second. Multiply your value by its factor to L/s (L/min → ÷60, m³/h → ×0.27778, US GPM → ×0.063090, UK GPM → ×0.075768, CFM → ×0.47195), then divide by the target unit's factor. For US GPM to L/min it simplifies to value × 3.785. The tool applies this two-step method for any pair.

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    Does the tool work offline, and does it upload my data?

    It works fully offline once the page has loaded, and it never uploads anything. All conversions are pure arithmetic using fixed factors, so the calculation happens on your own device — no server, no account, no tracking. That makes it dependable on site with no signal, and private by design, since there's nothing to send anywhere.

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