Two-Stroke Fuel Mix
Oil to add for a two-stroke gas:oil mix (chainsaws, trimmers, outboards).
Example
You enter
- Mix ratio (X in X:1) 50
- Fuel amount 1
- Fuel unit gallon
You get
- Oil to add 2.56
- Oil ml 75.71
- Dose 2.56
Checked against published worked examples from: STIHL Inc.
Details, formula, and sources
ScopeOil volume = fuel volume / ratio, reported in fl oz and mL with the per-gallon and per-liter dose (first-principles volume arithmetic).
Formula or tableoil volume = fuel volume / ratio (gas:oil by volume); 1 US gallon = 128 fl oz; 1 fl oz = 29.5735295625 mL; oz per gallon = 128 / ratio.
Source and editionTwo-stroke fuel/oil mixing by volume ratio; first-principles volume arithmetic, public domain. The oil grade and ratio are set by the equipment manufacturer.
Free accessPure arithmetic, public; modern air-cooled two-strokes are commonly 50:1 with a JASO/ISO oil, but the equipment manual governs.
What governsEstimate. AHJ and licensed professional govern.
API field namesratio, fuel_amount, fuel_unit, oil_oz, oil_ml, oz_per_gallon
- Ratio by volume the X:1 ratio is gas:oil by volume, the small-engine conventionequipment manufacturer specification