Flow Rate Converter
Convert a volumetric flow rate between US and imperial gallons, liters, cubic meters and cubic feet per second, minute, hour or day. Add a volume to see how long a pump, hose or pipe takes to fill or drain it.
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For example a pool, tank or pond.
How to use the Flow Rate Converter
- Enter the flow rate, for example 10 for a 10 GPM hose.
- Choose From and To units; every other unit appears in the results.
- Add a volume (optional), such as a pool size, to get the fill or drain time.
- Check the volume table for how much flows per hour, day or year.
- Copy the results or download a table as CSV.
Flow rate conversion factors
A volumetric flow rate is a volume divided by time. The converter turns your value into liters per second and then into the target unit, using exact definitions: 1 US gallon = 3.785411784 L, 1 imperial gallon = 4.54609 L and 1 cubic foot = 28.316846592 L.
| 1 unit | L/min | US GPM | m³/h |
|---|---|---|---|
| 1 US GPM | 3.7854 | 1 | 0.22712 |
| 1 UK GPM | 4.5461 | 1.2009 | 0.27277 |
| 1 GPH | 0.06309 | 0.016667 | 0.0037854 |
| 1 L/s | 60 | 15.850 | 3.6 |
| 1 m³/h | 16.667 | 4.4029 | 1 |
| 1 CFM | 28.317 | 7.4805 | 1.6990 |
| 1 CFS | 1,699.0 | 448.83 | 101.94 |
| 1 MGD | 2,628.8 | 694.44 | 157.73 |
Typical flow rates
- Bathroom faucet: 1.5 GPM or less for WaterSense-labeled models (about 5.7 L/min).
- Showerhead: 2.5 GPM is the US federal maximum; WaterSense models use 2.0 GPM or less.
- Garden hose: roughly 9-17 GPM for a ⅝ in hose, depending on water pressure.
- Bathroom exhaust fan: often 50-110 CFM of air.
- Rivers and streams: measured in CFS or m³/s (1 m³/s ≈ 35.31 CFS).
Tips
- Pump ratings are usually given at a specific head (height and pipe friction). The real flow at your installation is often lower.
- To measure a flow at home, time how long it takes to fill a bucket of known size: GPM = gallons ÷ seconds × 60.
- Air flow in CFM changes with pressure and temperature; this converter converts volume only, not mass flow.
Frequently asked questions
How do I convert GPM to LPM?
Multiply US gallons per minute by 3.785412, the number of liters in a US gallon. 10 GPM × 3.785 = 37.85 L/min. To convert LPM to GPM, divide by 3.785412.
How do I convert CFM to GPM?
One cubic foot holds 7.48052 US gallons, so GPM = CFM × 7.48052. 1 CFM ≈ 7.48 GPM. CFM is mostly used for air, but the volume conversion is the same for any fluid.
How many GPM is 1 m³/h?
1 m³/h = 1,000 liters per hour = 16.667 L/min ≈ 4.403 US GPM. Pump curves outside the US are often given in m³/h.
What is MGD?
MGD means million US gallons per day, the usual unit for water and wastewater treatment plants. 1 MGD ≈ 694.4 GPM ≈ 43.81 L/s ≈ 1.547 CFS.
How long will it take to fill my pool?
Divide the pool volume by the flow rate. A 15,000-gallon pool filled by a 10 GPM hose takes 15,000 ÷ 10 = 1,500 minutes, or 25 hours. Enter your pool volume in the optional field to get the exact time.
Are US and imperial gallons the same?
No. A US gallon is 3.785 liters and an imperial (UK) gallon is 4.546 liters, about 20% larger. So 10 UK GPM = 12.01 US GPM. Check which gallon a pump or meter uses.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.