2-Stroke Oil Mix Calculator

Work out how much 2-stroke oil to mix with petrol for chainsaws, trimmers, outboards and mopeds.

Mix ratio (fuel : 1 oil)	50 : 1
Fuel amount	1
Fuel in	US gallons

Mix ratio (fuel : 1 oil)

: 1

Fuel amount

Fuel in

Oil to add

76 mL(2.56 US fl oz)

For 3.79 L of fuel at 50:1. Use the ratio in your engine's manual and 2-stroke oil rated for it.

Oil per amount of fuel

Fuel	25:1	32:1	40:1	50:1
1 US gal	151 mL	118 mL	95 mL	76 mL
2.5 US gal	379 mL	296 mL	237 mL	189 mL
1 L	40 mL	31 mL	25 mL	20 mL
5 L	200 mL	156 mL	125 mL	100 mL

About the 2-Stroke Oil Mix Calculator

Enter the fuel-to-oil ratio and how much fuel you're mixing, in litres or gallons. The calculator gives the oil to add in millilitres and fluid ounces.

Two-stroke engines are lubricated by oil mixed into the fuel. The ratio, such as 50:1, means 50 parts fuel to 1 part oil, so 1 US gallon (3,785 mL) needs 76 mL (2.6 fl oz) of oil. Too little oil can seize the engine; too much causes smoke and fouled plugs. Follow your manufacturer's ratio.

The formula

Oil = fuel volume ÷ ratio

Worked example

1 US gallon of fuel at 50:1

3,785 mL ÷ 50 = 76 mL of oil
About 2.6 US fl oz

Questions people ask

How much oil for 1 gallon at 50:1?

2.6 US fl oz (76 mL).

How much for 5 litres at 40:1?

125 mL.

How much oil for 5 litres at 50:1?

100 mL (5,000 ÷ 50).