STIHL Chainsaw Fuel Mix Ratio Calculator
Work out exactly how much two-stroke oil to add to your petrol for a perfect STIHL fuel mix. Enter your fuel amount and ratio to get precise oil quantities in ml.
Fuel & Ratio Details
Enter your petrol amount and mix ratio to get the exact oil quantity
The quantity of petrol you’re mixing.
Choose the unit your petrol amount is measured in.
Check your fuel cap or operator’s manual for the ratio specified for your saw.
Fuel Mix Result
Oil quantity needed for your petrol mix
Enter your petrol amount and mix ratio above, then click Calculate Oil Needed to see exactly how much two-stroke oil to add.
Common STIHL Mix Ratios
STIHL specifies a 50:1 fuel-to-oil ratio for most current chainsaws using genuine STIHL two-stroke oil. Use the chart below for quick reference at common fuel amounts.
| Petrol Amount | Oil at 50:1 | Oil at 25:1 |
|---|---|---|
| 1 litre | 20 ml | 40 ml |
| 2 litres | 40 ml | 80 ml |
| 5 litres | 100 ml | 200 ml |
| 10 litres | 200 ml | 400 ml |
| 20 litres | 400 ml | 800 ml |
| 1 UK gallon | 91 ml | 182 ml |
STIHL Fuel Mix FAQ
Everything you need to know about mixing fuel for your STIHL chainsaw, storage, and getting the ratio right every time.
Most modern STIHL chainsaws run on a 50:1 petrol-to-oil ratio when using STIHL HP or HP Ultra two-stroke oil. Some older STIHL models specify 25:1, so it’s worth checking the fuel cap, operator’s manual, or engine housing for the exact ratio stamped on your particular saw.
For a 50:1 ratio, add 20ml of two-stroke oil to every litre of petrol. Scaled up, that’s 100ml of oil per 5 litres, or 200ml of oil per 10 litres of fuel.
No. Chainsaws use a two-stroke engine that mixes oil directly with the fuel for lubrication, so only oil specifically formulated for air-cooled two-stroke engines should be used. Regular four-stroke motor oil does not mix properly with petrol and will cause fouled spark plugs, poor lubrication, and engine damage.
Mixed fuel should generally be used within 30 to 60 days. Petrol starts to degrade and separate from the oil over time, which can lead to hard starting, reduced power, and gumming inside the carburettor, so only mix as much fuel as you expect to use within a month or two.
Too little oil starves the engine of lubrication, leading to overheating, scoring of the piston and cylinder, and premature engine failure. Too much oil causes excessive smoke, fouled spark plugs, carbon build-up, and poor performance, so it pays to measure the ratio accurately rather than estimate it by eye.