2 stroke oil mix calculator
This 2 stroke oil mix calculator gives the oil for your ratio and fuel amount: at 50:1, 1 US gallon of fuel needs 2.6 fl oz of oil. It also works in litres, with your own ratio, and in reverse.
Example: What would you like to calculate: Oil for a mix ratio · Mix ratio (fuel : oil): 50:1 (2 %) · Fuel amount 5 · Units: Litres and millilitres → Result: 100 ml of oil for 5 l of fuel (50:1). Source: Wikipedia – Zweitaktmotor (Gemischschmierung, Mischungsverhältnisse). Updated: .
How it is calculated
A ratio of 50:1 means 50 parts of fuel to 1 part of oil. That is 20 ml of oil per litre of petrol, or 2 percent of the fuel volume.
How it is calculated
The oil in ml is the fuel in litres times 1000, divided by the ratio N. At 25:1 that is 40 ml per litre, at 40:1 25 ml and at 100:1 only 10 ml. The share of the finished mix is slightly smaller than the share of the fuel: 1.96 percent at 50:1. For US gallons the calculator uses 3.785 litres and gives the oil in fluid ounces (fl oz).
Which ratio is right?
The equipment maker decides: chainsaws, brush cutters and mopeds state it in the manual. Fully and semi-synthetic oils often allow 50:1 or less oil, while mineral oil and the break-in period call for more. Too little oil makes the engine run hot and can seize the piston, too much fouls the spark plug and exhaust.
- Mix only as much fuel as you will use within a few weeks, because mixed fuel ages.
- Put the oil in the can first, then the petrol, and shake well.
- The table shows typical fill-ups from 1 to 20 litres, or 0.5 to 5 gallons.
Frequently asked questions
How much oil for 1 gallon of gas at 50:1?
About 2.56 fl oz (76 ml) of two-stroke oil. At 40:1 it is 3.2 fl oz and at 32:1 4 fl oz.
What does 2 percent oil mean in a two-stroke mix?
2 percent oil equals 50:1, that is 20 ml of oil per litre of fuel.
How do I work out the ratio from my amounts?
Choose “Mix ratio from my amounts” and enter the fuel and oil. 5 litres and 125 ml give 40:1.
Sources and legal basis
- Wikipedia – Zweitaktmotor (Gemischschmierung, Mischungsverhältnisse)
- Wikipedia – Two-stroke oil (mixing ratios, lubrication of the two-stroke engine)
- NIST – conversion of US gallon and ounce to SI units (NIST Handbook 44, Appendix C)
As of: · Editorial policy
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