Get the exact oil-to-fuel ratio for your chainsaw, whipper snipper, blower or brushcutter. Enter your fuel amount (or pick a jerry can size), choose your ratio, and get the precise amount of oil to add.
Ratios checked against Stihl and Husqvarna's own published specificationsWorks out oil from fuel, or fuel from oil — whichever you've got on hand.
Save your own tools and their ratios for one-tap access next time — handy with a shed full of different brands.
Your saved tools live only in this browser. Export a backup so they're not lost if this browser's data ever gets cleared, or to move them to another device.
A starting point only — tap a row to load it into the calculator, but always confirm against your tool's own manual or fuel cap, since ratios genuinely vary by model, engine age, and which oil you use.
A few things worth knowing before you fill up.
A 2-stroke engine has no separate oil reservoir like a car or a 4-stroke mower — the oil mixed into the fuel is the only lubrication the internal parts get. Too little oil and the engine can seize permanently, often without warning. Too much oil won't destroy the engine outright, but it causes smoky exhaust, fouled spark plugs, carbon build-up, and poor performance over time. Neither direction is something to guess at.
This trips a lot of people up: Stihl specifies 50:1 with genuine STIHL 2-stroke oil, but 25:1 if you're using a different oil brand. It's not that the tool changed — it's that cheaper or non-approved oils aren't formulated to the same lubrication standard, so more of it is needed to do the same job. Always check which ratio applies to the specific oil in your hand, not just the tool.
Once petrol and oil are mixed, most manufacturers recommend using it within 30 days. Ethanol-blended fuels absorb moisture over time and can separate or degrade, which is a common cause of hard starting and rough running in tools that sit unused for a season. Mix only what you'll realistically use in the next month, and always shake the container before refuelling since oil and fuel separate on standing.
The industry trend has been toward leaner 50:1 ratios as engines and full-synthetic oils have improved, but older-technology engines and many budget or entry-level tools are still specified at a richer 25:1 or 32:1. If you're not sure and can't find the manual, check the fuel cap or the plate on the tool itself — the ratio is very often printed right there.