SettingsSettings for this calculationUS
The flow rate in litres per second.
Litres per second is the unit of instantaneous demand: pump duties, fire-fighting flows, drainage design and the peak a water main has to deliver. It suits anything sized for the worst moment rather than the average, which is why hydraulic calculations use it even where the billing is in cubic metres.
Flow rate
72 m³/h
3,600 seconds per hour ÷ 1,000 litres per cubic metre = 3.6. Exact by definition. Name the fluid whenever you quote a flow rate in either unit.
- Litres per second entered
- 20 L/s
- Cubic metres per hour
- 72 m³/h
- Litres per minute
- 1,200 L/min
They open the calculator with your figures already in it
Litres per Second to Cubic Metres per Hour Calculator: 72 m³/h — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- SI Brochure, 9th edition — the litre is 10⁻³ m³ and the hour 3,600 s, from which the factor of 3.6 follows exactly
- NIST SP 811 — SI prefixes and the accepted non-SI units litre and hour
Inputs used
- Flow rate (L/s)
- 20
Intermediate steps
- Litres per second entered
- 20 L/s
- Cubic metres per hour
- 72 m³/h
- Litres per minute
- 1,200 L/min
Confidence note: 3,600 seconds per hour ÷ 1,000 litres per cubic metre = 3.6. Exact by definition. Name the fluid whenever you quote a flow rate in either unit.
Add the equipment this sizes
This result is a specification — 72 m³/h — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
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 2026-09-12 · v1.0.0
Regulatory standards & verification citations2
- SI Brochure, 9th edition — the litre is 10⁻³ m³ and the hour 3,600 s, from which the factor of 3.6 follows exactly
- NIST SP 811 — SI prefixes and the accepted non-SI units litre and hour
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.
The site already converted each of these two units into CFM and neither into the other, which is the shape a catalogue takes when it grows outward from one market: every metric unit gets a bridge to the imperial one and no bridge to its metric neighbour. In practice the neighbours meet more often than either meets CFM. A pump is selected in litres per second, the plant it feeds is rated in cubic metres per hour, and the person reconciling the two is doing it inside one metric system with no imperial unit anywhere in sight. The factor is 3.6 and entirely memorable, so the page earns its place less by doing the arithmetic than by carrying the litres-per-minute row and by being findable at all.