Gas Oil Ratio Calculator

This gas/oil ratio calculator can be used for determining the amount of oil needed for any gas/oil ratio required by the manufacturer's instructions for two-stroke engines.

How to use this calculator:

  1. Input the required gas/oil ratio.
  2. Input the quantity of gasoline in US gallons, UK gallons or liters.
  3. Click the "Calculate" button to find the quantity of oil required.
Gas Oil Mix Ratio Calculator

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You'll need to add:


Two-stroke (sometimes called 2-cycle) engines run on a mixture of gasoline and oil. When the substances are mixed, they both lubricate the engine and create combustion. All two-stroke engines are designed for a particular ratio of gas/oil mixture. To check you have the right ratio for the engine you're using, check in the operating manual. If you put gasoline in a two-stroke engine without oil in the engine will fail.

This calculator allows you to work out the exact ratio of oil and gas needed for any two-stroke engines.

How to mix oil and gas

Step 1: Begin by checking you are using the right measurement, as different countries use different units, i.e. liters, UK gallons, or US gallons. Find the correct oil/gas ratio for your particular engine. A number of fuel ratios may be used, e.g., 24:1, 32:1, 40:1, 50:1, etc. The ratio tells you the quantity of fresh standard unleaded gasoline (10% ethanol or lower) is needed for a specific quantity of oil.

Step 2: Mixing should take place in a fuel can, not inside the tank.

Step 3: Once you have mixed the fuel, pour it into the tank and you're good to go. Use the same ratio and operations every time your engine needs more fuel.

Formulas & Examples

The Gas Oil Ratio Calculator employs the basic formulas below:

((128 * US Gallons) / Ratio) = US Ounces of Oil

((160 * UK Gallons) / Ratio) = UK Ounces of Oil

((1000 * Liters) / Ratio) = Milliliters of Oil

Example 1: You've got 1 US gallon of gas, and your engine needs a gas/oil mix of 40:1. There are 128 oz in 1 US Gallon. You'll have to add ((128 × 1) / 40) = 3.2 US ounces of oil.

Example 2: You've got 5 UK gallons of gas, and your engine needs a gas/oil mix of 32:1. You'll have to add ((160 × 5) / 32) = 25 UK ounces of oil.


You may also be interested in our Alternative Fuels Conversion Calculator

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