Fuel Mixture 101 – Chainsaw Gas Mix Guide

| Last Updated: February 12, 2021

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Suppose you want reliability and power from your chainsaw.

In that case, it's important to pay close attention to your fuel mixture as this will determine the effectiveness and efficiency provided.

Below is a guide to help you understand the chainsaw fuel mixture, as well as a calculator to help you get your mixes right.

Chainsaw Gas Mix Calculator

Chainsaw Gas Oil Ratio - How Much Do I Mix of Each? 

Most chainsaws today will use either a 40:1 or 50:1 mixture. This means 40/50 parts gas to 1 part oil.

So, for example, if you were to make a 40:1 ratio, it would be 40 parts gas, which is equal to 1 gallon of gas mixed with 1 part oil, equal to 3.2 0z. A 50:1 ratio would be 1 gallon of gas mixed with 2.5 0z of oil. 

The regulatory standard is 40:1, but you can use either 40:1 or 50:1 in your chainsaw, but it's always best to follow the manufacturer's recommendations. It's also worth noting that 50:1 is the cleaner option in terms of exhaust emissions. 

How to Mix Chainsaw Gas 

You can find pre-made fuel mixtures on Amazon, but we're going to show you how to create your own fuel mixture. 

The best way to do this is by creating the mixture before putting it into your fuel tank. If you have any leftovers, you can store them for up to three months. 

  1. A 40:1 mixture would be 1 gallon of gas mixed with 3.2 0z of oil; a 50:1 mixture would be 1 gallon of gas mixed with 2.5 0z of oil. 

  2. Clean the outside of the fuel tank and threads to ensure no old fuel mixture build up contaminates the new fuel mixture.

  3. Use a funnel to slowly pour the fuel mixture into your fuel tank. 

  4. Secure the fuel cap tightly and give it a shake to ensure it's been mixed properly. 

Frequently Asked Questions 

We've compiled and answered some frequently asked questions to help you understand fuel mixtures better. 

What is 50 to 1 Ratio?

A 50:1 ratio is better for the environment as it doesn't create as much exhaust fumes. To measure a standard 50:1 fuel mixture, mix 1 gallon of gas to 2.5 0z of oil. 

What is a 40 to 1 Ratio?

A 40:1 ratio uses 1 gallon of gas to 3.2 0z; this is also the regulatory standard for chainsaw fuel mixtures. If you have an older chainsaw, they tend to have a 30:1 fuel mixture. 

What is a 1:1 Ratio?

A 1:1 ratio would consist of 1 gallon of gas mixed with 128 ounces of oil. 

What is Petrol Fuel?

Petrol fuel is a non-renewable fuel source made from crude oil; the difference between a petrol fuel and the oil that's used in the fuel mixture is that the latter consists of chemical compounds that are artificially created. 

What Happens If You Mix Premium And Regular Gas?

Any fuel above 91 octanes can be considered premium quality. 87 is known as just a regular quality fuel. If you mixed the two, the quality would balance out, and your modern chainsaw can adapt to the difference. However, this should only be done in an emergency as it can affect your chainsaw if used constantly. 

What Octane Gas For STIHL Chainsaw?

STIHL chainsaws are made to operate on high octane unleaded gas. They're designed to operate on fuel 89 octane or higher. 

What is The Oil Gas Ratio For A Husqvarna Chainsaw? 

A 50:1 fuel mixture is what a Husqvarna chainsaw requires to operate. 


Fuel mixtures can be difficult to work out by yourself, especially when you're not the greatest at math. But, everything we've mentioned above is what a chainsaw user will need to know when refueling their chainsaw.