Gas Oil Mix Ratio Calculator for Stihl Chainsaws
Work out exactly how much 2-stroke oil to mix with your gas. Enter your fuel amount and ratio to get the precise oil amount and total mixed fuel volume.
Fuel & Mixing Details
Enter your gas amount and ratio to get the exact oil amount
Total amount of gasoline you’re mixing. 1 US gallon = 128 fl oz = 3.785 litres.
Most modern Stihl chainsaws call for 50:1 with Stihl HP or HP Ultra oil — always confirm against your owner’s manual.
Your Mix Breakdown
Exact oil amount and total mixed fuel volume
Enter your gas amount and ratio above, then click Calculate Mix Ratio to see exactly how much oil to add.
50:1 Oil Amounts by Container Size
The most common ratio for modern Stihl chainsaws — quick reference for typical fuel container sizes.
| Gas Amount | Oil Needed (50:1) | Context / Details |
|---|---|---|
| 1 Gallon | 2.6 fl oz | Common small fuel can size |
| 2.5 Gallons | 6.4 fl oz | Standard mid-size fuel can |
| 5 Gallons | 12.8 fl oz | Large fuel can for extended use |
| 1 Litre | 20 ml | Metric equivalent, common oil bottle marking |
| 5 Litres | 100 ml | Metric equivalent for larger containers |
Stihl Fuel Mixing FAQ
Everything you need to know about gas-to-oil ratios, mixing, and fuel storage for your chainsaw.
Most modern Stihl chainsaws use a 50:1 gas to oil ratio when mixed with Stihl HP or HP Ultra two-stroke oil. Always check the owner’s manual for your specific chainsaw model, since a small number of older or specialty models may call for a different ratio.
It’s best to mix to the ratio specified in your chainsaw’s manual rather than assuming based on the oil bottle’s marked ratio. Using too much oil can cause excess smoke and spark plug fouling, while too little oil increases the risk of engine wear, so measure to your saw’s actual required ratio.
Mixed 2-stroke fuel is best used within about 30 days, since gasoline begins to degrade and separate from the oil over time, which can lead to poor starting, rough running, or engine damage. Mix only as much as you expect to use in that period and store it in an approved fuel container.
A chainsaw’s two-stroke engine has no separate oil sump, so the oil mixed into the fuel is what lubricates the piston, cylinder, and bearings as it burns. Using the wrong ratio or a low-quality oil can lead to inadequate lubrication, increased wear, and potential engine failure.
Stihl recommends its own HP or HP Ultra two-stroke oils, which are formulated for its engines, but a quality air-cooled 2-stroke oil designed for the correct ratio can generally work as well. Check your chainsaw’s manual for any manufacturer-specific recommendations before substituting.