2-Stroke Oil Mix Calculator
| Gas at 50:1 | Oil (ml) | Oil (fl oz) |
|---|---|---|
| 1 L | 20 ml | 0.68 |
| 5 L | 100 ml | 3.4 |
| 10 L | 200 ml | 6.8 |
| 1 US gal (3.79 L) | 76 ml | 2.6 |
Every 2-stroke engine - chainsaw, string trimmer, leaf blower, dirt bike - burns its lubrication mixed into the gasoline, and the ratio on the equipment (usually 50:1, sometimes 40:1 or 32:1) means parts of GAS to parts of OIL. At 50:1, one litre of gas takes exactly 20 millilitres of oil; one US gallon takes 2.6 fluid ounces. The ratio is set by the engine manufacturer and it is not a preference: too little oil and the piston seals and bearings score in minutes, too much and the plug fouls, the engine smokes, and the spark arrestor cokes up.
Two habits make the mixing foolproof: mix in a dedicated approved container, and mix fresh - premixed gas degrades as the oil separates over weeks, which is why the pros mix small batches per job. Modern synthetic oils at the correct ratio outperform the old 25:1 mineral era; the engines of the 1970s needed more oil because the oils were worse, not because the engines were tougher.
How to use
- Find the ratio on the equipment - the shroud, the manual, or the oil bottle's chart (50:1 for most modern handhelds).
- Enter the gas amount you are mixing in litres or gallons - the tool gives oil in ml and fluid ounces.
- Mix in the container, shake, and label it with the ratio and date; use premix within a month for best results.
Frequently asked questions
How much oil do I mix with 5 litres of gas at 50:1?
100 millilitres - divide the gas by 50 (5,000 ml divided by 50). At 40:1 the same 5 litres takes 125 ml, and at 32:1 it takes 156 ml. The calculator converts any amount either way, including US gallons to fluid ounces.
What happens if I use the wrong 2-stroke ratio?
Too little oil is the expensive direction: two-strokes rely on the mix for lubrication, and oil-starved pistons score the cylinder wall within minutes - the repair costs more than the tool. Too much oil fouls the spark plug, smokes heavily and builds carbon in the exhaust - annoying and fixable, which is why an honest mistake should err rich.
Can I use premix left over from last season?
Not reliably: gasoline ages (loses volatility in weeks) and the oil gradually separates from the gas, so old premix runs lean on oil even if the ratio was right when mixed. Mix what you will use within about a month, and stabilize or drain the tank for seasonal storage.
Is 50:1 the same everywhere in the world?
The ratio is universal but the packaging differs: US bottles are sized in fluid ounces per gallon (2.6 oz for 50:1), metric countries in millilitres per litre (20 ml per litre) - same mix, two dialects. Modern synthetic TC-W3 or ISO-L-EGD oils at 50:1 protect better than the 25:1 mineral oils the ratio nostalgia remembers.