Liters per Hour to Milliliters per Minute Converter
Common Conversions
| L/h | mL/min |
|---|---|
| 0.1 | 1.667 |
| 0.5 | 8.333 |
| 1 | 16.667 |
| 2 | 33.333 |
| 5 | 83.333 |
| 10 | 166.667 |
| 25 | 416.667 |
| 50 | 833.333 |
| 100 | 1666.667 |
| 1000 | 16666.667 |
Why this conversion matters in chemistry
Bioreactor feed-rate control is a place this matters. A 2 L/hr glycerol feed into a 1000 L CHO-cell bioreactor for an antibody production campaign is 33.3 mL/min on the analytical-side flow-rate display. Worth doing carefully when a process-control system logs in L/hr but a downstream HPLC titer assay or a real-time metabolic-flux calculation expects mL/min. The ratio of 16.6667 mL/min per L/hr is 1000 mL/L divided by 60 min/hr — a clean geometric ratio.
Formula
Where the factor comes from
This is the point where the decimal system runs into the sexagesimal one. The numerator contributes 1000 mL per liter, exact by SI prefix. The denominator contributes 60 minutes per hour, exact because the minute and the hour, although not SI units, are accepted for use with SI and defined as whole multiples of the second. The factor is therefore 1000/60, which reduces to 50/3 — exact as a rational number and impossible as a decimal, since it repeats forever as 16.666… The 16.6667 a converter displays is a rounding of an exact quantity, an unusual thing to find in the volume family. Every purely metric volume factor is a power of ten; it takes the minute in the denominator to introduce the three that spoils the decimal.
Precision and significant figures
Because 50/3 does not terminate, the arithmetic contributes its own small error: multiplying by 16.6667 instead of the exact fraction shifts the result by about two parts per million. That is far below anything a pump delivers. A lab peristaltic head is repeatable to perhaps a percent, and its absolute accuracy is worse than that until it has been calibrated by collecting and weighing the output; tubing age and occlusion move it further. Syringe drives do better. Two or three figures on the converted rate is the honest report, and it pays to keep display resolution separate from delivered accuracy — a setpoint field that accepts four digits is no evidence that four digits reach the vessel.
Worked Examples
A slow continuous-feed rate for a fixed-bed catalytic reactor.
A typical preparative-chromatography flow rate.
An analytical HPLC flow rate — the standard mL/min figure.
Common mistakes
A rounded setpoint integrates into real volume
Rounding 16.667 mL/min up to 17 looks harmless on the display and is a two percent bias on the delivered volume. Over an eight-hour feed that is an extra 160 mL of reagent charged, and the discrepancy surfaces as a mass-balance closure problem rather than as an obviously wrong flow. Set the pump to the unrounded figure if it accepts one, or account for the rounding in the total.
The logged L/h may not be volumetric
Process historians often derive a volumetric rate from a mass flow meter using a density entered at commissioning. If the fluid, its temperature or its composition has shifted since, the L/h figure already contains that stale density, and converting it to mL/min carries the assumption along untouched. Check what the tag is actually measuring before treating the converted number as a delivered volume.
Hourly averages hide a pulsed delivery
A controller reporting L/h is usually showing an average over minutes, while a figure in mL/min reads as an instantaneous rate. Diaphragm and peristaltic pumps deliver in discrete strokes, so the true instantaneous rate swings well above and below the converted value. For anything sensitive to momentary concentration at the inlet, the averaged number is the wrong quantity whatever the units.