Flow Converter

Flow rate — more precisely, volumetric flow rate — measures how much volume of a fluid moves past a given point over a period of time. It's one of the most practical quantities in fluid systems, describing everything from how fast water moves through a pipe to how much oil a well produces per day.

Our Flow converter supports a wide range of units grouped into a few families. The SI-based units — cubic meter/second, cubic meter/day, cubic meter/hour, and cubic meter/minute — along with cubic centimeter and milliliter variants at each of those time scales, cover the metric system used in most scientific and international engineering work. Liter-based units (liter/day, liter/hour, liter/minute, liter/second) are the everyday metric units seen on water meters, pumps, and household appliance specifications.

For US and imperial measurement, the converter includes gallon (US) and gallon (UK) per day, hour, minute, and second — useful since the two gallon definitions differ in size — along with barrel (US) and kilobarrel (US) per unit time, the standard units for oil production and refining. Acre-foot per year, day, and hour describe large water volumes used in agriculture and reservoir management, while hundred-cubic-foot units appear on US natural gas and water utility bills. Cubic yard, cubic foot, and cubic inch per unit time round out the imperial volumetric options, and ounce (US and UK) per unit time cover smaller-scale flows.

To use the converter, select your starting and target units from the dropdown lists and enter a value — the result is calculated instantly to up to 12 significant digits. For example, converting 100 US gallons per minute to liters per second gives about 6.31 L/s, a conversion frequently needed when comparing US pump specifications to European ones.

Flow rate conversions are essential across many industries: civil and environmental engineers use them for stormwater and river flow calculations (often in cubic feet per second); oil and gas engineers work in barrels per day; municipal water utilities bill in hundred-cubic-foot units or gallons; agricultural engineers plan irrigation in acre-feet; and HVAC and plumbing professionals size equipment using gallons or liters per minute. Because flow rate specifications arrive in whatever unit a particular industry or country happens to use, having one reliable converter that handles all of them saves significant time and prevents costly unit-mismatch errors.

Flow rate also connects directly to two other quantities used elsewhere in this Fluids Converters section: multiply a volumetric flow rate by fluid density to get a mass flow rate, or divide it by a pipe's cross-sectional area to get a velocity — so a precise, correctly-converted flow figure from this tool is often the starting point for a pump sizing calculation, a heat exchanger design, or a mass-balance check elsewhere in a project.

All conversion factors used here are drawn from standard, internationally recognized definitions of volume and time units, so you can trust the results whether you're checking a pump curve, converting a utility bill, or sizing piping for a new system. The converter is free, requires no account, and works equally well on desktop and mobile devices.