Gas to Oil Calculator

Two-Stroke Gas to Oil Ratio Calculator

Calculate the exact amount of 2-cycle oil needed for your fuel mix.

US Gallons Liters
: 1

Common ratios: 50:1 (Chainsaws), 40:1 (Trimmers), 32:1 (Older Outboards)

Required Oil:

How to Mix Two-Stroke Fuel Correcty

Using the correct gas-to-oil ratio is critical for the lifespan of 2-stroke engines found in lawnmowers, chainsaws, and dirt bikes. Since these engines do not have an internal oil reservoir, the oil mixed into the gasoline provides the only lubrication for the piston and crankshaft.

Understanding the Ratios

A ratio like 50:1 means that for every 50 parts of gasoline, you need 1 part of two-cycle oil. If you add too little oil (lean mix), the engine will overheat and seize. If you add too much oil (rich mix), the engine will smoke excessively, foul the spark plug, and build up carbon.

Common Mix Examples

  • 50:1 Ratio: 2.6 US fl. oz of oil per 1 gallon of gas.
  • 40:1 Ratio: 3.2 US fl. oz of oil per 1 gallon of gas.
  • 32:1 Ratio: 4.0 US fl. oz of oil per 1 gallon of gas.
  • 25:1 Ratio: 5.12 US fl. oz of oil per 1 gallon of gas.

Mixing Tips

  1. Always use fresh, high-octane gasoline (89 or higher is often recommended).
  2. Use a dedicated 2-cycle engine oil (not motor oil for cars).
  3. Pour the oil into a clean gas can first, then add the gasoline. This helps the liquids mix naturally.
  4. Shake the container vigorously before refueling your equipment to ensure the oil hasn't settled.
function calculateOilMix() { var gasVolume = parseFloat(document.getElementById('gasVolume').value); var gasUnit = document.getElementById('gasUnit').value; var ratioValue = parseFloat(document.getElementById('mixRatio').value); var resultArea = document.getElementById('resultArea'); var oilOutput = document.getElementById('oilOutput'); var mixDescription = document.getElementById('mixDescription'); if (isNaN(gasVolume) || gasVolume <= 0 || isNaN(ratioValue) || ratioValue <= 0) { alert('Please enter valid positive numbers for both gas volume and ratio.'); return; } var oilInOunces = 0; var oilInML = 0; var oilInLiters = 0; if (gasUnit === 'gallons') { // 1 Gallon = 128 Fluid Ounces var totalGasOunces = gasVolume * 128; oilInOunces = totalGasOunces / ratioValue; oilInML = oilInOunces * 29.5735; oilOutput.innerHTML = oilInOunces.toFixed(2) + ' US fl oz (' + Math.round(oilInML) + ' ml)'; mixDescription.innerHTML = 'To achieve a ' + ratioValue + ':1 ratio, add ' + oilInOunces.toFixed(2) + ' ounces of 2-cycle oil to ' + gasVolume + ' gallons of gas.'; } else { // 1 Liter = 1000 Milliliters var totalGasML = gasVolume * 1000; oilInML = totalGasML / ratioValue; if (oilInML >= 1000) { oilInLiters = oilInML / 1000; oilOutput.innerHTML = oilInLiters.toFixed(2) + ' Liters (' + Math.round(oilInML) + ' ml)'; } else { oilOutput.innerHTML = Math.round(oilInML) + ' ml'; } mixDescription.innerHTML = 'To achieve a ' + ratioValue + ':1 ratio, add ' + Math.round(oilInML) + ' ml of 2-cycle oil to ' + gasVolume + ' liters of gas.'; } resultArea.style.display = 'block'; }

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