Flow rate is just volume divided by time
Liters per minute measures how much liquid passes a point in one minute. Rearrange the same equation to get the other two answers: fill volume is flow rate × time, and fill time is volume ÷ flow rate. A 1,000-liter tank at 50 L/min fills in 20 minutes.
Convert L/min to other flow units
| From 1 L/min | Equals | Factor |
|---|---|---|
| US gallons/min (GPM) | 0.264 gal/min | × 0.2642 |
| UK gallons/min | 0.220 gal/min | × 0.2200 |
| Cubic meters/hour | 0.06 m³/h | × 0.06 |
| Liters/second | 0.0167 L/s | ÷ 60 |
| US gallons/hour | 15.85 gal/h | × 15.85 |
"GPM" almost always means US gallons in North American plumbing specs; a UK gallon is about 20% bigger, so a UK figure looks smaller for the same real flow.
Typical flow rates to sanity-check your number
- Bathroom tap. 6–12 L/min for washing hands and dishes.
- Water-saving shower. 6–9 L/min; an unrestricted one can be double that.
- Garden hose. 10–20 L/min, depending on tap pressure and hose bore.
- Sump/transfer pump. 50–150 L/min for draining or moving water fast.
Flow drops with pipe length and pressure loss, and old, scaled pipes can flow 20–40% less than new ones. Take the average of several timed measurements rather than one.
Common questions
How do I measure flow rate without a meter?
Use the bucket method. Run the water into a container of known size and time how long it takes to fill. Flow rate equals volume divided by time, so a 10-liter bucket filled in 40 seconds is 15 liters per minute.
How do I convert L/min to m3/h?
Multiply by 0.06. For example, 100 L/min is 6 cubic meters per hour. To go the other way, divide by 0.06.
Is a US gallon the same as a UK gallon here?
No. One US gallon is 3.785 liters and one UK (imperial) gallon is 4.546 liters, about 20 percent larger. So 1 L/min is 0.264 US gal/min but only 0.220 UK gal/min. Always check which gallon a spec means.
