How much oil for 5 L petrol at 1:50?

100 ml. Calculate: 5 × 1000 / 50 = 100 ml.

What is the most common ratio?

Modern devices often 1:50, older ones 1:25 or 1:33. Check the manual.

Fuel Mix Ratio Calculator

Calculate how much two-stroke oil to add to petrol at a chosen mix ratio (e.g. 1:50).

Amount of petrol: 5.00 litres

Mix ratio (1:X): 1:50

100 ml

Oil needed

Oil	100 ml
Total mixture	5.10 litres

ℹ️ Oil (ml) = petrol (L) × 1000 / ratio. Check the correct ratio in your device manual.

The fuel mix ratio calculator tells you how much two-stroke oil to add to petrol at a chosen ratio. It is handy for mixing fuel for a lawnmower, brush cutter, chainsaw or outboard motor.

How the calculator works and what it’s for▾

How the oil amount is calculated

The oil needed in millilitres is the amount of petrol in litres multiplied by a thousand and divided by the ratio number. For a 1:50 mix, 50 is the divisor.

For example, 5 litres of petrol at 1:50 needs 5 times 1000 divided by 50, which is 100 millilitres of two-stroke oil.

What you enter and what you get

You enter the amount of petrol in litres and the mix ratio in the form 1:X. The calculator shows the oil needed in millilitres and the total volume of the finished mixture.

A ratio of 1:50 means one part oil to fifty parts petrol. A smaller second number means a richer mix with more oil.

Who it suits

The calculator helps anyone who maintains two-stroke garden machines or boats and wants to mix fuel in the right proportion without guesswork.

Important to remember

Always check the correct ratio in your device's manual, since it varies by machine and oil type. The wrong ratio can damage the engine, so use the calculator only once you know the right ratio.

🔄 Reviewed June 2026