Chainsaw Fuel Mix Calculator: How Much 2-Stroke Oil per Gallon?

What is the mix ratio for a chainsaw?

Check your manual first: your maker’s ratio is the right one. STIHL, Husqvarna and ECHO list 50:1 for most of their tools, which means 50 parts gas to 1 part 2-stroke oil.

Here is what three makers say:

• STIHL: most STIHL gas-powered equipment runs on a 50:1 mix.
• Husqvarna: 50:1 with Husqvarna 2-stroke oil, or 33:1 with other brands of 2-stroke oil.
• ECHO: its PowerBlend Gold oil mixes at 50:1.
• Other tools may call for 40:1, 32:1 or another ratio. Your manual or the oil bottle tells you.

What do pros use? Our crews run a 50:1 mix. Your saw may need something different, so follow your own saw maker’s manual.

How much oil do I mix with gas?

Ounces of oil = gallons of gas × 128 ÷ the ratio. In metric, milliliters of oil = liters of gas × 1,000 ÷ the ratio.

Ounces of 2-stroke oil

Milliliters of 2-stroke oil

• Example: 2.5 gallons of gas at 50:1. 2.5 × 128 ÷ 50 = 6.4 ounces of oil.
• Example: 5 liters of gas at 50:1. 5 × 1,000 ÷ 50 = 100 mL of oil.
• Measure the oil carefully, especially for small batches. Husqvarna warns that small errors can change the ratio a lot.

What does 50:1 mean?

It means 50 parts gas to 1 part oil. Put another way, the oil is about 2% of the mix.

• 33:1 is about 3% oil, and 25:1 is about 4%.
• A lower first number means more oil in each gallon.

What kind of gas and oil should I use?

Use the gas and oil your manual names. Here is what the makers say:

• STIHL: mid-grade unleaded gas, at least 89 octane, with no more than 10% ethanol (E10). STIHL says more than 10% ethanol may damage the equipment and may void the warranty.
• Husqvarna: unleaded, ethanol-free gas, unless you use its premixed fuel.
• ECHO: 89 octane or higher, mixed with its PowerBlend Gold oil. Check your manual for the most ethanol your ECHO tool can take.
• Oil: use 2-stroke (also called 2-cycle) engine oil. Husqvarna says never to use outboard boat motor oil (rated TC-W) or 4-stroke car oil in these tools.

How do I mix chainsaw fuel?

Use a clean, approved gas can, and keep one can just for mixed fuel. That way it never ends up in a 4-stroke engine by mistake.

• STIHL’s way: pour the oil into the can first. Add the gas. Close the can and shake it to mix.
• Husqvarna’s way: put in half the gas, add all the oil, and shake gently. Then add the rest of the gas.
• Clean the gas cap and the area around it before you fill the saw.

How long does mixed gas last?

Mix only what you will use in about a month. STIHL says not to use fuel mix older than 60 days, and better no older than 30, even with a stabilizer; Husqvarna says to avoid storing mixed fuel for more than a month.

• A fuel stabilizer can help, but check your maker’s limit.
• Putting the saw away? STIHL says that if a tool will sit unused for more than 30 days, store it “dry”: empty the tank, then run the engine until the fuel is used up.

Can I use the same mix in my trimmer and blower?

Yes, if the tool has a 2-stroke engine and its manual gives the same ratio. Some makers use one ratio for most of their gas tools; for example, STIHL says most of its gas-powered equipment runs on 50:1.

• 4-stroke tools don’t take mixed fuel. They use regular gas, with the oil kept separate.
• Check each tool’s manual before you share one can of mix.