Chainsaws and Wood
2-Cycle Fuel Mix Ratio Chart: 50:1, 40:1, 32:1 and 25:1
Quick answer
At 50:1, mix 2.6 fluid ounces of 2-stroke oil per gallon of gasoline, or 20 milliliters per liter. At 40:1 use 3.2 ounces per gallon, at 32:1 use 4.0 ounces and at 25:1 use 5.1 ounces. Most modern handheld tools specify 50:1.
Two-stroke engines in string trimmers, leaf blowers, chainsaws and hedge trimmers have no oil sump, so the oil that lubricates the engine is carried in the fuel. Too little oil can score the piston and seize the engine, and too much causes smoke, fouled plugs and carbon buildup.
Find your ratio across the top of the chart and your fuel quantity down the left. The ratio printed in your operator manual or on the fuel cap always governs. The 2-cycle mix ratio calculator does any quantity in between.
On this page
How much 2-stroke oil per gallon of gas?
| Gasoline | 50:1 | 40:1 | 32:1 | 25:1 |
|---|---|---|---|---|
| 0.5 gallon | 1.3 oz | 1.6 oz | 2.0 oz | 2.6 oz |
| 1 gallon | 2.6 oz | 3.2 oz | 4.0 oz | 5.1 oz |
| 1.5 gallons | 3.8 oz | 4.8 oz | 6.0 oz | 7.7 oz |
| 2 gallons | 5.1 oz | 6.4 oz | 8.0 oz | 10.2 oz |
| 2.5 gallons | 6.4 oz | 8.0 oz | 10.0 oz | 12.8 oz |
| 5 gallons | 12.8 oz | 16.0 oz | 20.0 oz | 25.6 oz |
| 6 gallons | 15.4 oz | 19.2 oz | 24.0 oz | 30.7 oz |
One US gallon is 128 fluid ounces, so oil ounces = gallons x 128 / ratio. Two tablespoons equal about 1 fluid ounce.
How much 2-stroke oil per liter?
| Gasoline | 50:1 | 40:1 | 32:1 | 25:1 |
|---|---|---|---|---|
| 1 liter | 20 ml | 25 ml | 31 ml | 40 ml |
| 2 liters | 40 ml | 50 ml | 63 ml | 80 ml |
| 4 liters | 80 ml | 100 ml | 125 ml | 160 ml |
| 5 liters | 100 ml | 125 ml | 156 ml | 200 ml |
| 10 liters | 200 ml | 250 ml | 313 ml | 400 ml |
| 20 liters | 400 ml | 500 ml | 625 ml | 800 ml |
Milliliters of oil = liters x 1,000 / ratio.
What mix ratio does my engine use?
| Equipment | Typical ratio | Notes |
|---|---|---|
| Modern handheld trimmers, blowers, chainsaws, hedge trimmers | 50:1 is common | Many current engines specify 50:1 with a JASO FD or ISO-L-EGD oil |
| Older or some import handheld engines | 40:1 | Check the manual or the label on the fuel cap |
| Older chainsaws and vintage equipment | 32:1 or 25:1 | Many older engines were designed for richer mixes |
| Push mowers, riding mowers, snow blowers, pressure washers | Do not mix oil into the fuel | These are 4-stroke engines with a separate oil sump |
Your operator manual governs. Using an approved oil at the specified ratio also matters for warranty coverage.
How do I mix 2-cycle fuel correctly?
- Use fresh gasoline. Use fresh unleaded gasoline of the octane and ethanol content your manual allows, commonly 89 octane or higher and no more than 10 percent ethanol. E15 and higher blends are not approved for small engines.
- Use a dedicated can. Mix in a clean, approved fuel can that is clearly marked for mixed fuel, so it is never poured into a 4-stroke mower or snow blower.
- Add half the gas, then the oil. Pour in about half the gasoline, add the full measured amount of 2-stroke oil, then add the rest of the gasoline so the oil disperses evenly.
- Shake and label it. Close the can, shake it well, and write the ratio and the date on the can.
- Shake again before each fill. Oil can separate over time, so shake before fueling, and refuel only with the engine off and cool.
- Use it within about 30 days. Many manufacturers recommend using mixed fuel within about 30 days unless a stabilizer is added. Stale fuel is the most common reason a trimmer will not start after storage.
What happens if I use the wrong mix ratio?
Too little oil is the dangerous mistake. Running a 32:1 engine on 50:1, or forgetting the oil entirely, reduces lubrication and can score the cylinder and seize the engine, which is usually not covered by warranty. Too much oil is messier but milder: heavy smoke, spark plug fouling and carbon buildup on the exhaust port and spark arrestor, which costs power over time.
Never put mixed fuel into a 4-stroke engine such as a push mower, riding mower or snow blower, which carry their own oil in the crankcase. If mixing fuel is a chore you would rather drop entirely, battery tools such as the EGO ST1623T trimmer and the EGO CS1815 chainsaw need no fuel at all. The trade-offs are in gas vs battery chainsaw.
Which oils and premix should I buy?
For regular users, pre-measured bottles keep ratios exact. For occasional users, sealed ethanol-free premix avoids both mixing errors and stale fuel. Tools that use it are in the best string trimmers and the best chainsaws.
ECHO Power Blend Gold 50:1 2-Stroke Oil, 6 Pack
$16.99Six pre-measured bottles, each sized for 1 gallon of gasoline at 50:1, which removes measuring error entirely.
Best for: anyone mixing a gallon at a time
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VP Racing SEF 50:1 Ethanol-Free Premix Fuel, Quart 3 Pack
$29.82Sealed ethanol-free fuel already mixed at 50:1, which stores far longer than pump gas and cannot be mixed wrong.
Best for: tools used a few times a year
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Husqvarna X-Guard All Season Bar and Chain Oil, 1 Gallon
$24.95A separate oil for the bar and chain reservoir, which is not the same thing as 2-stroke mix oil and must never be substituted for it.
Best for: every chainsaw and pole saw owner
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Husqvarna 130L 28cc Straight Shaft Gas String Trimmer
$279.00A 28cc straight shaft gas trimmer with an 18 inch cutting width, typical of the handheld engines that specify a 50:1 mix.
Best for: rural lots, ditches and fence lines
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ECHO CS-590 Timber Wolf 59.8cc 20 in. Gas Chainsaw
$478.99A 59.8cc, 20 inch gas saw for firewood cutting, the kind of engine where using the wrong ratio is an expensive mistake.
Best for: firewood and storm cleanup
Check price on AmazonHow we chose
We did not test these products in person. Picks are researched from manufacturer specifications and owner manuals, engine and safety certifications where they apply, warranty terms, public recall records, and the recurring themes in verified owner reviews. We favor established brands with large review counts and parts support, match each pick to a real yard size or task, and place it in the tier where its price and capability actually belong.
Frequently asked questions
How many ounces of oil for 1 gallon at 50:1?
For 1 US gallon of gasoline at 50:1, add 2.6 fluid ounces of 2-stroke oil, since 128 divided by 50 is 2.56. Many oils are sold in 2.6 ounce bottles for exactly this reason. For 2.5 gallons add 6.4 ounces, and for 5 gallons add 12.8 ounces. Two tablespoons is roughly 1 fluid ounce if you have no measure.
What is the difference between 40:1 and 50:1?
A 40:1 mix carries more oil: 3.2 ounces per gallon against 2.6 ounces, about 25 percent more. Use the ratio your engine specifies. Running a 50:1 engine on 40:1 usually causes some extra smoke and deposits, while running a 40:1 engine on 50:1 reduces lubrication, which is the riskier direction to be wrong in.
Can I use 50:1 mix in a 40:1 engine?
It is not recommended. An engine designed for 40:1 expects more oil, and a leaner 50:1 mix reduces lubrication, which can increase wear or damage the piston and cylinder. Follow the manual. If you own tools that specify different ratios, keep separate clearly labeled cans rather than trying to split the difference with one mix.
How much oil for 5 liters of gas at 50:1?
Add 100 milliliters of 2-stroke oil, since 5,000 divided by 50 is 100. At 40:1 the same 5 liters needs 125 milliliters, at 32:1 about 156 milliliters and at 25:1 200 milliliters. A measuring cup marked in milliliters or a graduated ratio bottle makes metric mixing straightforward.
Does the brand of 2-stroke oil matter?
Use a quality air-cooled 2-stroke oil meeting the standard your manual lists, commonly JASO FD or ISO-L-EGD for modern handheld engines. Some manufacturers require their own or an approved oil for warranty coverage. Marine outboard oils are formulated for water-cooled engines and are not a substitute unless the equipment maker approves them.
Researched, not professional advice. This page is compiled from published specifications, manuals, labels and owner-review consensus, not hands-on testing. Follow the manufacturer's instructions and product label, and consult a qualified professional where safety, chemicals, fuel or structures are involved. As an Amazon Associate we earn from qualifying purchases.