Where does this come up in plumbing or irrigation work?

Common cases: comparing a US-rated sump pump, well pump, or sprinkler head's GPM spec against a European or metric-labeled product's LPM rating.

Is this the same as GPH (gallons per hour)?

No — GPH is a different time unit. Multiply GPM by 60 to get GPH, or divide GPH by 60 to get GPM, before comparing to an LPM figure if needed.

Does this apply to any liquid?

Yes — this is a pure volumetric flow rate conversion and doesn't depend on what liquid is flowing.

Is a British pump's GPM the same gallon?

Often not, and the difference is a fifth. This page converts US gallons, where 1 GPM is 3.785 L/min. British pump, boiler and shower literature that still quotes GPM usually means the imperial gallon of 4.546 litres — so 10 GPM from a UK datasheet is 45.5 L/min, not the 37.9 this page returns. Check which gallon the datasheet uses before comparing two flows.

Measurements & Conversions

GPM to LPM Calculator

Convert flow rate between gallons per minute and liters per minute for pumps and irrigation.

Answers as you typeNo submit button
Every formula citedNamed published standards
Calculated in your browserNo account, nothing uploaded

SettingsSettings for this calculationUS

Market

Imperial · sales tax

Flow rate (GPM or LPM)

The flow rate value to convert.

Useful for comparing a US-rated pump or sprinkler head (GPM) against a metric spec sheet (LPM).

Converting From

The unit your starting value is in.

The result shows the equivalent in the other unit.

Converted flow rate

37.85 LPM

High confidence

Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

1 US gallon = 3.785411784 litres, exactly

Inputs used

Flow rate (GPM or LPM): 10
Converting From: Gallons per minute (GPM)

Final result37.85 LPM

Add the equipment this sizes

This result is a specification — 37.85 LPM — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

QtyItemPrice each ($)

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-08-26 · in the site-wide review of 2026-09-06 · v1.0.0

Regulatory standards & verification citations1

1 US gallon = 3.785411784 litres, exactly

Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

How to calculate GPM to LPM in 3 steps

Flow rate (GPM or LPM)The flow rate value to convert.
Converting FromThe unit your starting value is in.
Converted flow rateThe tool computes the converted flow rate from those figures and shows the formula, its sources, and a confidence rating alongside it.

GPM to LPM at common values

Page defaults, not your figures above.

Flow rate (GPM or LPM)	Converted flow rate (LPM)
1	3.79
2	7.57
5	18.9
10	37.9
20	75.7
50	189
100	379

Frequently asked questions

Where does this come up in plumbing or irrigation work?: Common cases: comparing a US-rated sump pump, well pump, or sprinkler head's GPM spec against a European or metric-labeled product's LPM rating.
Is this the same as GPH (gallons per hour)?: No — GPH is a different time unit. Multiply GPM by 60 to get GPH, or divide GPH by 60 to get GPM, before comparing to an LPM figure if needed.
Does this apply to any liquid?: Yes — this is a pure volumetric flow rate conversion and doesn't depend on what liquid is flowing.
Is a British pump's GPM the same gallon?: Often not, and the difference is a fifth. This page converts US gallons, where 1 GPM is 3.785 L/min. British pump, boiler and shower literature that still quotes GPM usually means the imperial gallon of 4.546 litres — so 10 GPM from a UK datasheet is 45.5 L/min, not the 37.9 this page returns. Check which gallon the datasheet uses before comparing two flows.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.