Calculator Inputs
Enter blend components. Use a factor for simple non-linearity or correction.
Example Data Table
Sample blend inputs and a typical estimated output format.
| Component | Volume (L) | RON | MON | Factor |
|---|---|---|---|---|
| Base Fuel | 40 | 91 | 83 | 1.00 |
| Ethanol | 10 | 109 | 90 | 1.05 |
| Toluene | 5 | 114 | 109 | 1.00 |
| Estimated Output | RON ≈ 97.9, MON ≈ 88.4, AKI ≈ 93.2 (illustrative) | |||
Formula Used
This estimator uses a volume-weighted blend model with an optional per-component factor:
- TotalVolume = Σ(Vᵢ)
- BlendRON = (Σ(Vᵢ × RONᵢ × fᵢ)) / TotalVolume
- BlendMON = (Σ(Vᵢ × MONᵢ × fᵢ)) / TotalVolume
- AKI = (BlendRON + BlendMON) / 2
- Sensitivity = BlendRON − BlendMON
The conservative offset subtracts the same number of octane points from both RON and MON. It is not a laboratory standard, but a planning aid.
How to Use This Calculator
- Choose the volume unit you will enter for all components.
- Enter base fuel volume, then its RON and MON values.
- Add each blend component with volume, RON, MON, and factor.
- Use factor 1.00 for simple linear blending assumptions.
- Optionally apply a conservative offset for planning margins.
- Click Estimate Octane to view results above the form.
- Use CSV or PDF downloads to archive your blend assumptions.
Blend Inputs and Measurement Terms
Octane describes a fuel's resistance to knock under controlled tests. RON reflects mild operating conditions, while MON reflects hotter, higher-load operation. Many stations display AKI, the average of RON and MON, because it correlates with typical vehicle requirements. This calculator accepts component RON and MON to keep those distinctions visible. When you enter volumes, the tool converts them to liters internally to keep calculations consistent.
Volume Weighting and Additive Factors
For planning, a first-pass blend estimate uses a volume-weighted average: each component contributes in proportion to its share of total volume. Real blends can deviate due to interaction effects, especially with oxygenates and aromatics. The blending factor field provides a controlled adjustment range so engineers can apply known correction behavior from internal data or prior test campaigns. Keep factors close to 1.00 unless you have evidence.
Interpreting AKI for Engine Matching
Higher compression ratios and advanced ignition timing demand greater knock resistance. Use the estimated AKI to compare candidate blends against an engine's required grade, then verify on a calibrated test method before deployment. If you are evaluating multiple blend recipes, keep your base fuel constant and change one variable at a time. That approach improves traceability and makes later lab correlation easier.
Sensitivity and Operating Conditions
Sensitivity is RON minus MON and indicates how performance may shift with temperature and load. A high sensitivity blend can look strong in RON yet lose margin in severe service. Turbocharged applications, high ambient conditions, and towing loads tend to emphasize MON. When sensitivity rises, consider monitoring both metrics instead of relying on a single headline number. The conservative offset can emulate a safety margin for uncertain inputs.
Quality Checks and Documentation Outputs
Before relying on results, check units, confirm all component volumes are positive, and ensure RON and MON values are sourced from trustworthy specifications. Small data-entry errors can dominate the estimate when additive volumes are low but octane values are high. After running a scenario, export CSV for spreadsheets and PDF for reports to document assumptions, factors, and computed metrics. This supports review, repeatability, and audit trails. Store batch notes, dates, and sources beside each run.
FAQs
1) What does the calculator estimate?
An engineering estimate of blended RON, MON, AKI, and sensitivity from your entered component volumes, octane values, and optional blending factors. It supports comparisons and documentation, not certification.
2) Why do I need both RON and MON?
RON and MON represent different test severities. Using both lets you compute AKI and see sensitivity, which helps judge how a blend may behave under higher temperature and load.
3) When should I change the blending factor?
Adjust it only when you have test data or supplier guidance showing non-linear blending for a component. Otherwise keep 1.00 so the estimate remains a transparent volume-weighted average.
4) What is the conservative offset used for?
It subtracts the same octane points from both RON and MON to represent uncertainty or safety margin in inputs. Use it for planning buffers, not to replace proper testing.
5) Can I mix liters and gallons in one run?
No. Choose one unit for all entries. The tool converts your chosen unit to liters internally, then uses that consistent basis for the weighted calculations.
6) How do the CSV and PDF downloads help?
CSV supports spreadsheet analysis and scenario tracking. PDF provides a compact report of inputs, factors, and results for reviews, approvals, and audit trails.