2 Cycle Calculator

2-Cycle Fuel Mix Calculator

US Gallons / Fluid Ounces Liters / Milliliters

: 1

Mixing Required:

function updateLabels() { var unit = document.getElementById("unitType").value; var label = document.getElementById("fuelLabel"); if (unit === "US") { label.innerText = "Amount of Gasoline (Gallons)"; } else { label.innerText = "Amount of Gasoline (Liters)"; } } function calculateMix() { var fuel = parseFloat(document.getElementById("fuelAmount").value); var ratio = parseFloat(document.getElementById("ratioPart").value); var unit = document.getElementById("unitType").value; var resultDiv = document.getElementById("mixResult"); var oilReqText = document.getElementById("oilRequirement"); var summaryText = document.getElementById("ratioSummary"); if (isNaN(fuel) || fuel <= 0 || isNaN(ratio) || ratio <= 0) { alert("Please enter valid positive numbers for fuel and ratio."); return; } var oilAmount; var unitName; if (unit === "US") { // 1 Gallon = 128 Fluid Ounces oilAmount = (fuel * 128) / ratio; unitName = "Fluid Ounces (fl oz)"; } else { // 1 Liter = 1000 Milliliters oilAmount = (fuel * 1000) / ratio; unitName = "Milliliters (ml)"; } oilReqText.innerText = "Add " + oilAmount.toFixed(2) + " " + unitName + " of oil"; summaryText.innerText = "To achieve a " + ratio + ":1 mix with " + fuel + " " + (unit === "US" ? "gallons" : "liters") + " of gas."; resultDiv.style.display = "block"; }

Understanding 2-Cycle Fuel Ratios

A 2-cycle engine (or two-stroke engine) differs from a standard 4-cycle car engine because it does not have a dedicated oil reservoir and pump system. Instead, lubrication for the internal crankshaft, bearings, and cylinder walls is provided by mixing specialized two-cycle oil directly into the gasoline.

Getting the ratio right is critical for the longevity of your equipment. Too little oil causes excessive friction and heat, leading to "seizing" the engine. Too much oil results in heavy smoke, spark plug fouling, and carbon buildup in the exhaust port.

Common 2-Cycle Mix Ratios

Most modern outdoor power equipment requires one of the following three ratios:

• 50:1 Ratio: Common in modern high-end brands like Stihl and Husqvarna. (Approximately 2.6 oz of oil per 1 gallon of gas).
• 40:1 Ratio: Frequently used for mid-sized equipment like Ryobi or Poulan trimmers. (Approximately 3.2 oz of oil per 1 gallon of gas).
• 32:1 Ratio: Often found in older vintage machinery or high-performance racing engines. (4.0 oz of oil per 1 gallon of gas).

How to Mix Your Fuel Safely

1. Check the Manual: Always verify the required ratio on the engine's fuel cap or in the operator's manual.
2. Use Fresh Fuel: Use 89 octane or higher and ensure it has no more than 10% ethanol. Ethanol attracts moisture, which can damage small engines.
3. Pour Oil First: If you are using a dedicated gas can, pour the oil in first, then add the gasoline. This helps the oil disperse and mix thoroughly through the agitation of the gasoline pour.
4. Shake Well: Always give the gas can a gentle shake before fueling your equipment, as the oil can settle over time.

Example Calculation (US Standard)

If you have a 2.5-gallon gas container and your chainsaw requires a 50:1 ratio:

Step 1: 2.5 Gallons x 128 (oz per gallon) = 320 Total Ounces of Fluid
Step 2: 320 / 50 (the ratio) = 6.4 Ounces of Oil

By using the 2-cycle calculator above, you can avoid the manual math and ensure your equipment runs smoothly without the risk of engine failure.