Flow Rate Converter
Convert flow rate between units instantly. Includes conversion tables, common equivalents, and calculation formulas. Includes formulas and worked examples.
Formula
Converted Flow = Input x (From Factor / To Factor); Velocity = Flow Rate / Pipe Area
Each flow rate unit has a conversion factor to liters per minute (LPM) as the base unit. The input value is multiplied by the source factor and divided by the target factor. Fluid velocity through a pipe equals the volumetric flow rate divided by the pipe cross-sectional area (pi times radius squared).
Worked Examples
Example 1: Converting GPM to Liters per Minute
Problem: Convert 10 US gallons per minute to liters per minute.
Solution: L/min = GPM x 3.78541\nL/min = 10 x 3.78541 = 37.8541 L/min
Result: 10 GPM = 37.8541 L/min
Example 2: Flow Velocity in a Pipe
Problem: Find velocity for 20 L/min through a 1-inch (25.4mm) pipe.
Solution: Area = pi x (0.0127)^2 = 0.0005067 m2\nFlow = 20 / 60000 = 0.000333 m3/s\nVelocity = 0.000333 / 0.0005067 = 0.658 m/s
Result: Velocity: 0.658 m/s (2.158 ft/s)
Frequently Asked Questions
What is flow rate and how is it measured?
Flow rate is the volume of fluid passing through a point per unit time. It is commonly measured in liters per minute, gallons per minute, or cubic meters per hour depending on the application. Volumetric flow rate is calculated by multiplying the cross-sectional area of the pipe or channel by the average fluid velocity. Industrial flow meters use various principles including differential pressure, electromagnetic induction, ultrasonic transit time, and Coriolis force to measure flow rates accurately.
How do I calculate fluid velocity from flow rate and pipe diameter?
Fluid velocity equals the volumetric flow rate divided by the cross-sectional area of the pipe. The pipe area equals pi times the radius squared. For example, with a flow rate of 10 liters per minute through a 25mm diameter pipe: area = pi times 0.0125 squared = 0.000491 square meters. Converting 10 L/min to 0.000167 cubic meters per second, velocity = 0.000167 divided by 0.000491 = 0.340 meters per second. Higher velocity generally means more turbulence and pressure drop.
What is the difference between volumetric and mass flow rate?
Volumetric flow rate measures the volume of fluid passing per unit time (liters/min, gallons/min), while mass flow rate measures the mass passing per unit time (kg/s, lb/hr). They are related by fluid density: mass flow rate equals volumetric flow rate times density. For water at standard conditions, 1 liter per minute equals approximately 1 kilogram per minute. The distinction matters for gases, whose density changes significantly with temperature and pressure, making mass flow rate more reliable for gas metering.
What are typical flow rates for household plumbing?
Standard household fixtures have regulated flow rates to conserve water. Kitchen faucets typically deliver 6-8 liters per minute (1.5-2 GPM). Showerheads are limited to about 9.5 L/min (2.5 GPM) in the US. Toilets use 6 liters (1.6 gallons) per flush. A garden hose delivers 30-60 L/min (8-15 GPM). The main supply line to a house typically handles 40-75 L/min (10-20 GPM), and exceeding this can cause pressure drops throughout the home.
Can I share or bookmark my calculation?
You can bookmark the calculator page in your browser. Many calculators also display a shareable result summary you can copy. The page URL stays the same so returning to it will bring you back to the same tool.
What formula does Flow Rate Converter use?
The formula used is described in the Formula section on this page. It is based on widely accepted standards in the relevant field. If you need a specific reference or citation, the References section provides links to authoritative sources.