What is GPM?
GPM stands for Gallons Per Minute — a unit of liquid flow rate widely used in the United States. It tells you how many US liquid gallons pass a given point every minute. GPM is the standard unit for specifying the output of pumps, showerheads, faucets, irrigation systems, and industrial water treatment equipment.
A gallon can refer to either the US liquid gallon (≈ 3.785 liters) or the British imperial gallon (≈ 4.546 liters). Our GPM calculator uses the US liquid gallon by default, which is the global standard in pump and plumbing specifications.
How to Use the GPM Calculator
Our calculator works in three modes — select what you want to find from the "Calculate" drop-down, enter the two known values, then click Calculate.
- Find Flow Rate — enter Volume and Time. Example: a pump moves 50 US gallons in 5 minutes → flow rate = 10 GPM.
- Find Volume — enter Flow Rate and Time. Example: a 2 GPM shower running for 15 minutes uses 30 US gallons.
- Find Time — enter Volume and Flow Rate. Example: filling a 100-gallon tank at 4 GPM takes 25 minutes.
You can freely switch between US and Metric units at any time: choose liters, cubic meters, cubic feet, or any other volume unit from the selector. Time can be expressed in seconds, minutes, or hours. Flow rate can be shown in GPM, GPH, L/min, L/s, m³/h, or CFM.
GPM Formula
The flow rate formula is:
Flow Rate (GPM) = Volume (gallons) ÷ Time (minutes)
Re-arranged forms:
- Volume = Flow Rate × Time
- Time = Volume ÷ Flow Rate
Convert GPM to LPM and Other Units
Common conversions from 1 GPM (US):
| Unit | Value |
|---|---|
| 1 GPM (US gallons per minute) | = 3.7854 L/min |
| 1 GPM | = 0.0631 L/s |
| 1 GPM | = 60 GPH (gallons per hour) |
| 1 GPM | = 0.2271 m³/h |
| 1 GPM | = 0.1337 CFM (cubic feet per minute) |
| 1 L/min (LPM) | = 0.2642 GPM |
| 1 m³/h | = 4.4029 GPM |
To convert interactively — simply enter a value, switch the Flow Rate Unit selector, and the Results panel will show all equivalent values at once.
Typical GPM Values
| Device / Application | Typical Flow Rate |
|---|---|
| Standard shower (US) | 2 GPM (low-flow) – 2.5 GPM |
| Kitchen faucet | 1.5 – 2.2 GPM |
| Bathroom faucet | 0.5 – 1.5 GPM |
| Dishwasher | 1 – 2 GPM |
| Garden hose (standard) | 9 – 17 GPM |
| Fire hose (1.75 in) | 95 – 200 GPM |
| Residential well pump | 5 – 10 GPM |
FAQs
How many gallons per minute does a shower use?
A standard shower head in the US uses about 2 GPM. Older models may use 2.5 GPM or more, while ultra-low-flow models use as little as 1.5 GPM. A 10-minute shower at 2 GPM uses 20 US gallons of water.
What is a good GPM for a well pump?
A residential well should deliver at least 5 GPM for one or two people, and ideally 10 GPM or more for larger households. The required flow depends on the number of fixtures used simultaneously.
How do I convert GPM to LPM?
Multiply GPM by 3.7854 to get liters per minute (LPM). For example, 5 GPM × 3.7854 = 18.93 LPM. You can also use the calculator above — enter 5 in the Flow Rate field, set the unit to GPM, and the Results section will show LPM immediately.
Is GPM the same as gallons per minute?
Yes — GPM is the standard abbreviation for gallons per minute. Unless otherwise specified, GPM refers to US liquid gallons per minute.