Kilograms per Hour to Grams per Second Converter
Common Conversions
| kg/h | g/s |
|---|---|
| 0.1 | 0.028 |
| 0.5 | 0.139 |
| 1 | 0.278 |
| 2 | 0.556 |
| 5 | 1.389 |
| 10 | 2.778 |
| 25 | 6.944 |
| 50 | 13.889 |
| 100 | 27.778 |
| 1000 | 277.778 |
Why this conversion matters in chemistry
Spray-dry formulation work is the usual setting. A 10 kg/hr inlet feed for an amorphous solid dispersion API formulation is 2.78 g/s on the bench-scale sampling rate behind the analytical QC for particle-size distribution and residual solvent. In practice you reach for it when a process-spec hourly throughput ends up reported in the per-second form a real-time analyzer reports. A factor of 0.2778 g/s per kg/hr follows from the 1000 g/kg ÷ 3600 s/hr cancellation.
Formula
Where the factor comes from
Two exact relations meet here, one on each side of the fraction. The kilogram-to-gram step is the kilo prefix, a fixed decimal factor in the SI. The hour is not an SI unit at all, but it is accepted for use alongside them and fixed at exactly 3600 seconds. Carry the units through and the algebra is visible: 1 kg/h × (1000 g / 1 kg) × (1 h / 3600 s) = 1000/3600 g/s. Kilograms cancel, hours cancel, and 0.2777… g/s survives — the ratio reduces to 5/18, which is why the shorthand is division by 3.6. Nothing was measured, so the factor carries no uncertainty; the only awkwardness is that the quotient never terminates, so keep it as a fraction when the arithmetic continues past this step.
Precision and significant figures
The factor being exact means your result inherits exactly the figures the flow measurement supplied, and those are usually fewer than the display suggests. A Coriolis meter reading mass directly will specify a fraction of a percent of reading. A thermal mass flow controller is specified as a percent of full scale, so a device sized for 100 kg/h holds that same absolute error at a 5 kg/h setpoint, where it becomes a large relative one. There is also a time-averaging problem the units hide: a stated hourly throughput is typically a batch total divided by a run time, and rewriting it per second implies an instantaneous rate the number never carried. Two or three figures is honest for most process feeds.
Worked Examples
The reverse anchor — the cleanest small-scale process and bench conversion.
A small pilot-scale feed rate expressed per second.
A production-scale reactor throughput on the per-second scale.
Common mistakes
Multiplying by 3.6 instead of dividing
The mass step scales up by 1000 and the time step scales down by 3600, and the time step wins, so g/s is always the smaller number. If your per-second figure exceeds the kg/h figure, the operation went the wrong way. Keep 3.6 kg/h = 1 g/s in mind as the anchor — anything below that hourly rate must give a sub-unity g/s.
Mixing a per-second rate with minutes
Once the rate is in g/s, every downstream time must be in seconds too. A 45-minute run at 2.78 g/s delivers 2.78 × 2700 = 7500 g, or 7.5 kg. Multiply by 45 instead and you get 125 g, a number small enough to look like a sampling aliquot rather than a total charge, so nothing in the mass balance flags it.
Volumetric flow read as mass flow
Rotameters, and most gas controllers, respond to volume rather than mass. Converting L/min to kg/h needs a density, and for a gas that density moves with temperature and pressure. Thermal controllers add a second layer: they are calibrated on one gas and require a correction factor for anything else, so the displayed number is not a mass rate for the gas actually flowing.