This flow rate converter translates volumetric flow between L/min, L/s, m³/h, US GPM, and cubic feet per minute (CFM) — plumbing, HVAC and aquarium math in one table.

Flow = Volume ÷ Time, in Five Accents

The same water wears m³/h on a European pump curve, GPM on an American filter box, and L/min on an aquarium canister. Volumes themselves (how much the pool holds) are our Pool Volume Calculator. Part of our Conversion Calculators collection.

Anchor Conversions (Verified)

  • 1 m³/h = 16.67 L/min = 4.403 US GPM = 0.589 CFM — the defaults’ full row
  • Household feel: a shower ≈ 9.5 L/min (2.5 GPM); a garden hose ≈ 20–40 L/min; a pool pump 150–300 L/min (40–80 GPM)
  • Turnover math: a 50 m³ pool through a 10 m³/h pump turns over in 5 hours — the converter plus the volume is the whole filtration plan
  • CFM doubles as HVAC’s dialect (air): a bathroom fan at 80 CFM = 136 m³/h of air — different fluid, same arithmetic

Flow Pitfalls

  • UK gallons lurk in older pump specs: Imperial GPM is 20% larger — check which gallon before ordering.
  • Rated flow is at a stated head/pressure; real delivered flow falls as resistance rises (pump curves, not constants).
  • Velocity hides inside flow: the same 100 L/min is gentle in a 100 mm pipe and violent in a 25 mm one (continuity: Q = A·v).
  • Mass flow (kg/s) needs density — multiply volumetric flow by density from our Density Converter for process work.

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Frequently Asked Questions

How do I convert L/min to GPM?

Divide by 3.785 (US gallons): 100 L/min = 26.4 GPM. Reverse, multiply GPM by 3.785. For m³/h, multiply GPM by 0.2271. This converter renders the full five-unit row from any entry.

What is CFM?

Cubic feet per minute — the volumetric flow standard for air handling (HVAC, fans, compressors) and some US pump contexts. 1 CFM = 1.699 m³/h = 28.32 L/min. Context declares whether the fluid is air or water.

How long will a pump take to move a volume?

Time = volume ÷ flow: 50 m³ (50,000 L pool) at 10 m³/h takes 5 hours; at 250 L/min (15 m³/h), 3 h 20 min. Pair this converter with our Pool Volume Calculator for turnover planning.

Is GPM US or UK?

Both exist and differ 20% (Imperial gallon = 4.546 L vs US 3.785 L). Modern specs are overwhelmingly US GPM; vintage British equipment and some Commonwealth plumbing still speak Imperial — the converter here uses US gallons and says so on the label.

How does pipe size affect flow?

Flow Q and velocity v relate by Q = A·v through the pipe’s cross-section: halving diameter quarters area, quadrupling velocity (and friction losses climb steeply with velocity). Nameplate flow says nothing until the pipe agrees to carry it.

Is this flow rate converter free?

Yes — free, instant, no sign-up.