Blending Octane Calculator

Work out blending octane instantly with clear inputs, formula shown and shareable results.

About Blending Octane Calculator

Volumetric blending assumes octane blends linearly on volume: blend octane is the volume-weighted average of component octanes. Real blending is non-linear — aromatics and oxygenates show blending octane numbers different from their neat values — so refineries use blending indices calibrated from test data.

Formula

Volumetric octane blending

Blend octane = (V_A x RON_A + V_B x RON_B) / (V_A + V_B)

Worked example

With the default values below, Blending Octane Calculator returns Blend Octane of 95.900. Change any input above and every figure here is recalculated in your browser.

Inputs used

Volume Of Component Aminimum 0 m3: 700 m3
Octane Of Component Aaccepts 0–130 RON: 92 RON
Volume Of Component Bminimum 0 m3: 300 m3
Octane Of Component Baccepts 0–130 RON: 105 RON

Results

Blend Octane: 95.900
Total Blend Volume: 1,000.00
Octane Uplift Over Component A: 3.900
High-Octane Component Share: 30.00%

Step by step

1Values used
2Volumetric octane blending
3Blend Octane= 95.900
4Total Blend Volume= 1,000.00
5Octane Uplift Over Component A= 3.900
6High-Octane Component Share= 30.00

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why is real octane blending non-linear?

Octane response depends on interactions between hydrocarbon classes. Ethanol in particular blends with an effective octane well above its neat value at low concentrations, then tails off.

What is the difference between RON, MON and AKI?

RON is measured under mild conditions, MON under more severe ones. AKI, used in North America, is the average of the two and typically 8-10 numbers below RON for the same fuel.