Two-Stroke Fuel Mix Calculator
Find how much two-stroke oil to add to petrol for 50:1, 40:1, 32:1 or any other ratio, in millilitres and fluid ounces.
Use the ratio in your engine's manual or on the oil bottle.
Two-stroke oil to add
100 mL
- In US fluid ounces
- 3.38 fl oz
- Total mix
- 5.1 litres
For 5 litres of petrol at 50:1, add 100 mL of two-stroke oil.
How it's worked out
- Petrol in mL
5 litres × 1,0005,000 mL - Oil
5,000 mL ÷ 50100 mL
Oil for common amounts at 50:1
| Petrol | Oil |
|---|---|
| 1 L | 20 mL |
| 2 L | 40 mL |
| 4 L | 80 mL |
| 5 L | 100 mL |
| 10 L | 200 mL |
| 20 L | 400 mL |
- Pour in about half the petrol, add the oil, shake, then add the rest of the petrol and shake again.
- Mixed fuel doesn't keep for long, so mix only what you'll use soon; your engine's manual says how long it can be stored.
How it is worked out
The petrol is turned into millilitres, then divided by the ratio: oil = petrol ÷ ratio. The table shows the oil for common amounts at your ratio.
Mixing it
Pour about half the petrol into a clean can, add the oil, shake, then add the rest of the petrol and shake again. Mix only what you'll use soon.
Questions people ask
How much oil for 5 litres of petrol at 50:1?
100 mL. At 40:1 it's 125 mL, and at 25:1 it's 200 mL.
How much oil for a US gallon at 50:1?
About 76 mL, or 2.6 US fluid ounces.
What does 50:1 mean?
50 parts petrol to 1 part oil, so the oil is the petrol amount divided by 50.
Which ratio should I use?
The one in your engine's manual. Some oil bottles give a ratio too, but the engine maker's figure comes first.
About this calculator
Formula and rules last checked 10 November 2026Written and tested by the CalculatorDex teamReport a problem