Dilution Ratio Calculator
Compute an olfactometer’s dilution factor from clean-air and sample flows, and the concentration it presents to the panel.
Dilution result
The dilution factor is the total presented flow divided by the sample flow, Z = (Qclean + Qsample) / Qsample. Dividing a known raw concentration by that factor gives the concentration presented to the panel at this dilution step.
Dilution is the whole method
A dynamic olfactometer works by blending a measured trickle of odorous sample into a much larger stream of clean air, then stepping the ratio up or down until the panel’s response changes. Every result in olfactometry ultimately rests on how accurately those two flows — and therefore the dilution factor — are known.
This calculator makes that ratio explicit. Enter the clean and sample flows to see the factor, and add the raw sample concentration to see what the panel is actually presented with at that step. It is a planning and checking aid, not a replacement for a controlled instrument.
Frequently Asked Questions
How is the dilution factor calculated?
The dilution factor is the total flow presented to the panel divided by the odorous sample flow: Z = (clean air + sample) / sample. Adding 99 units of clean air to 1 unit of sample gives a factor of 100 — the sample makes up one hundredth of what the panel breathes.
What is clean or neutral air?
It is the dilution air an olfactometer adds to the sample — filtered, deodorised air (typically passed through activated carbon) that carries no odour of its own. Its purity is a big part of why olfactometry has to be done on calibrated equipment.
What does 'presented concentration' mean?
If you know the raw sample's odour concentration, dividing it by the dilution factor gives the concentration actually delivered to the panel's nose at that dilution step. A 10,000 ouE/m³ sample diluted 100-fold is presented at 100 ouE/m³.
Do the two flows need the same units?
Yes. Because the dilution factor is a ratio, the clean-air and sample flows must be in the same unit — litres per minute, cubic metres per hour, whatever you like — and the unit cancels out. Only the presented-concentration figure carries a real unit (ouE/m³).
Can I use this to calibrate a real olfactometer?
No. Real olfactometers control flows with mass-flow controllers and are calibrated and verified under EN 13725. This tool shows the underlying arithmetic so you can plan or check dilution steps, not certify an instrument.
Screening estimates only — not a substitute for accredited EN 13725 olfactometry, dispersion modelling, or regulatory advice.