Stihl Chainsaw Gas Mix Calculator
Calculate the exact amount of 2-stroke oil needed for your Stihl chainsaw. Official 50:1 mix ratio calculator for Stihl petrol chainsaws, strimmers, and blowers in the UK.
Stihl Fuel & Oil Details
Enter your fuel volume to calculate the exact 2-stroke oil required for your Stihl chainsaw
How much unleaded petrol do you have?
Select the unit of measurement for your fuel.
Stihl recommends 50:1 for almost all modern chainsaws.
Choose how you want the oil amount displayed.
Stihl Mix Calculation
Exact 2-stroke oil required for your Stihl equipment
Enter your fuel volume above, then click Calculate Stihl Mix to see the exact oil required.
Stihl Equipment Mix Ratios
Always check your specific model’s user manual, but here are the official Stihl recommendations for their most popular 2-stroke equipment in the UK.
| Equipment Type | Recommended Ratio | Oil per 5 Litres |
|---|---|---|
| Modern Stihl Chainsaws | 50:1 | 100 ml |
| Stihl Strimmers & Blowers | 50:1 | 100 ml |
| Stihl Cut-off Saws | 50:1 | 100 ml |
| Older Stihl Models (Pre-2000s) | 40:1 or 50:1 | 125 ml or 100 ml |
Stihl Fuel & Oil FAQ
Everything you need to know about mixing fuel for your Stihl chainsaw, choosing the right oil, and maintaining your 2-stroke engine.
Stihl officially recommends a 50:1 fuel-to-oil ratio for all their modern chainsaws and 2-stroke equipment. This means 50 parts of unleaded petrol to 1 part of high-quality 2-stroke engine oil (like Stihl HP or HP Ultra). For 1 litre of petrol, you need exactly 20ml of oil.
You should use clean, unleaded petrol with a minimum octane rating of 90 RON. Stihl recommends using ethanol-free fuel if possible, but if using E10 fuel (up to 10% ethanol), ensure it is fresh and do not store the mixed fuel for more than one month to prevent carburettor and fuel line damage.
Stihl highly recommends using their own branded oils, specifically Stihl HP (mineral) or Stihl HP Ultra (synthetic). These are specifically formulated for high-RPM air-cooled engines, burn cleanly, and help prevent carbon buildup and spark plug fouling.
Stihl advises that mixed fuel should not be stored for longer than one month. If you must store it, keep it in an approved fuel container in a cool, shaded place, and consider using a fuel stabiliser. Always shake the container thoroughly before use to ensure the oil has not settled.
While a 40:1 mix (which contains more oil) will not immediately destroy your engine, it will cause excessive smoking, heavy carbon buildup, and foul the spark plug. Modern Stihl engines are precisely tuned for a 50:1 ratio. Always follow the manufacturer’s recommendation in your user manual for optimal performance.