The conversions that come up in every design review, in one place. Put a value in, read every equivalent unit out - no rounding surprises, factors shown.
The factors are the standard SI and US customary definitions, not rounded industry shortcuts. Where a figure is quoted to five significant digits it is because the definition is exact to that point.
Not a general purpose converter - only the families where a unit mix-up changes a specification.
A tender in m³/h and a blower curve in cfm is the most common mix-up in aeration work. gpm and MGD still arrive from US references, and a factor-of-two error here doubles the plant you are pricing.
Quoted as m³/m²·h, m/h, mm/s or gpm/ft² depending on who wrote the brief. They describe the same rise rate, so convert rather than re-design.
mg/L, ppm and g/m³ are interchangeable in water. Percentage is the one that catches people out: 1% is 10,000 mg/L, not 100.
Diffuser data in kPa, blower data in metres of water column, instruments in bar or psi. One bar is 10.1972 m H₂O - close enough to 10 to tempt a wrong shortcut.
Process air is quoted in m³/h, m³/min or cfm. Because air is compressible, always state whether the figure is at standard conditions or at the blower discharge.
Carrier and media quantities are quoted by volume in m³ and by mass in kg or tonnes. Density is the bridge - and for media it is bulk density, not the density of the plastic itself.
The ones that come up most often in correspondence.
Multiply by 4.40287. One cubic metre per hour is 4.40287 US gallons per minute, because one US gallon is 3.785411784 litres. Going the other way, one gpm is about 0.2271 m³/h. The converter above does this and shows the other flow units at the same time.
Yes - for a clarifier, cubic metres per square metre per hour reduces to metres per hour, because the square metres cancel. That is why overflow rate is often quoted simply as a rise rate in m/h. One m/h is 0.40906 gpm/ft² and 0.27778 mm/s.
In water and wastewater work, yes - to the precision anyone uses. One litre of water is one kilogram, so one milligram per litre is one part per million by mass. The identity degrades only in very concentrated brines, where the solution density departs from 1 kg/L.
10.1972 m of water. One bar is 100 kPa, and a metre of water column is 9.80665 kPa, so dividing gives 10.1972. This is the conversion that matters when a diffuser specification is quoted in kPa and the blower data is in metres of head.
Once the units agree, the next step is usually one of these.
Send the flows, loadings and the standard you are working to - we will come back with the media and the quantity in the units your project uses.
Ask for a specification checkNo obligation - response within 24h (working days)