Chainsaws and Wood
2-Cycle Mix Ratio Calculator: Oil to Gas for 50:1, 40:1 and 32:1
Quick answer
At 50:1, mix 2.6 ounces of 2-stroke oil with 1 gallon of gasoline, or 20 milliliters with 1 liter. At 40:1 use 3.2 ounces per gallon, and at 32:1 use 4 ounces per gallon. Most modern handheld trimmers, blowers and chainsaws specify 50:1, but always use the ratio printed in your operator manual or on the fuel cap.
Two-stroke engines in string trimmers, leaf blowers, chainsaws and hedge trimmers have no oil sump, so the oil that lubricates the engine is mixed into the fuel. Too little oil can score the piston and seize the engine; too much causes smoke, carbon buildup and fouled plugs. Choose your ratio and how much fuel you are mixing, and the calculator gives the exact amount of oil in ounces and milliliters. Tired of mixing fuel? Compare with battery tools.
2-cycle mix ratio calculator
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ECHO Power Blend Gold 50:1 2-Stroke Oil, 6 Pack
$16.99Six 2.6 oz bottles of semi-synthetic 50:1 oil, each mixing one gallon of fuel, with stabilizers rated for one month in a sealed container.
Best for: mixing your own fuel for 2-stroke gear
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VP Racing SEF 50:1 Ethanol-Free Premix Fuel, Quart 3 Pack
$29.82Ready-to-pour 94 octane, ethanol-free 50:1 premix rated stable for 2 years in the tank and 5 years sealed.
Best for: seasonal gear that sits between uses
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Husqvarna X-Guard All Season Bar and Chain Oil, 1 Gallon
$24.95All-season high-tack bar and chain oil in a 1 gallon jug that reduces sling, friction and wear.
Best for: keeping any chainsaw or pole saw lubricated
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ECHO SRM-2620T 25.4cc High Torque Gas String Trimmer
$479.99Commercial high torque trimmer pairing a 25.4cc engine with the Speed-Feed head, built for dense weeds and daily professional use.
Best for: acreage, heavy brush and landscape crews
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Husqvarna 130L 28cc Straight Shaft Gas String Trimmer
$279.0028cc engine with an 18 in. cutting width, Smart Start and Air Purge for easier pulls and LowVib dampening; the straight shaft reaches under shrubs and fences.
Best for: rural lots, ditches and fence lines beyond battery range
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ECHO PB-580T 58.2cc Backpack Blower
$429.9958.2cc backpack blower rated at 510 CFM with a tube-mounted throttle, sized for homeowners and landscapers moving big leaf piles.
Best for: wooded half-acre to one-acre lots
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Husqvarna 150BT 51cc Backpack Blower
$297.99Husqvarna lists 765 CFM and 22 N of blowing force from a 51cc X-Torq engine, with a padded harness, hip belt and cruise control.
Best for: value-minded buyers wanting backpack gas power
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Husqvarna 450 Rancher 20 in. Gas Chainsaw
$354.9950.2cc, 3.2 HP X-Torq engine with Smart Start, Air Injection filtration and LowVib, rated for 13 to 20 in. bars.
Best for: firewood cutting and storm cleanup on rural property
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ECHO CS-590 Timber Wolf 59.8cc 20 in. Gas Chainsaw
$478.9959.8cc engine on a 20 in. bar, the largest displacement saw in this lineup for felling and bucking big hardwood.
Best for: woodlot owners felling and bucking large trees
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EGO Power+ ST1623T 16 in. String Trimmer Kit with 4.0Ah Battery
$299.00Auto-feeding LINE IQ head, POWERLOAD winding and a telescopic carbon fiber shaft, with EGO citing up to 60 minutes per charge on the included 4.0Ah battery.
Best for: large suburban lots where you never want to bump-feed line
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EGO Power+ CS1815 18 in. Chainsaw Kit with 6.0Ah Battery
$399.002500W brushless motor that EGO rates as a 50cc gas equivalent, with a color display, LED work light and up to 330 cuts on a 4x4 per charge.
Best for: battery users felling small trees and bucking firewood
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How much 2-stroke oil per gallon of gas?
| Gasoline | 50:1 | 40:1 | 32:1 | 25:1 |
|---|---|---|---|---|
| 0.5 gal | 1.3 oz | 1.6 oz | 2.0 oz | 2.6 oz |
| 1 gal | 2.6 oz | 3.2 oz | 4.0 oz | 5.1 oz |
| 2 gal | 5.1 oz | 6.4 oz | 8.0 oz | 10.2 oz |
| 2.5 gal | 6.4 oz | 8.0 oz | 10.0 oz | 12.8 oz |
| 5 gal | 12.8 oz | 16.0 oz | 20.0 oz | 25.6 oz |
How much 2-stroke oil per liter?
| Gasoline | 50:1 | 40:1 | 32:1 | 25:1 |
|---|---|---|---|---|
| 1 L | 20 ml | 25 ml | 31 ml | 40 ml |
| 2 L | 40 ml | 50 ml | 63 ml | 80 ml |
| 4 L | 80 ml | 100 ml | 125 ml | 160 ml |
| 5 L | 100 ml | 125 ml | 156 ml | 200 ml |
| 10 L | 200 ml | 250 ml | 313 ml | 400 ml |
What mix ratio does my engine use?
| Equipment | Typical ratio | Notes |
|---|---|---|
| Modern handheld (trimmers, blowers, chainsaws, hedge trimmers) | 50:1 is common | Many current Echo, Husqvarna and similar 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, generators | Do not mix oil into fuel | Most are 4-stroke engines with a separate oil sump |
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 ethanol blends are not approved for small engines.
- Use an approved fuel container. Mix in a clean, approved fuel can marked for mixed fuel so it is never used in 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 mixes evenly.
- Shake and label. Close the can and shake it well. Label the can with the ratio and date.
- Shake again before each fill. Oil can separate over time, so shake the can before fueling the tool, and refuel only with the engine off and cool.
How long does mixed 2-cycle fuel last?
Gasoline starts to degrade within weeks, and mixed fuel is no different. Many manufacturers recommend using mixed fuel within about 30 days unless a fuel stabilizer is added, and some 2-stroke oils include stabilizer. Stale fuel is the most common reason a trimmer or chainsaw will not start after storage. For occasional users, sealed ethanol-free premix such as the VP Racing SEF 50:1 Ethanol-Free Premix Fuel, Quart 3 Pack costs more per ounce but keeps far longer once sealed and avoids mixing errors. For regular use, a quality oil like the ECHO Power Blend Gold 50:1 2-Stroke Oil, 6 Pack in pre-measured bottles for 1 gallon keeps ratios exact.
What happens if I use the wrong mix ratio?
Too little oil, such as running a 32:1 engine on 50:1 or forgetting oil entirely, reduces lubrication and can score the cylinder and seize the engine, which usually is not covered by warranty. Too much oil, such as 32:1 in a 50:1 engine, causes heavy smoke, spark plug fouling and carbon buildup on the exhaust port and spark arrestor, which reduces power over time. Never put mixed fuel in a 4-stroke engine such as a push mower, riding mower or snow blower: they have their own oil in the crankcase and mixed fuel fouls plugs and leaves deposits. If this is a chore you would rather drop, battery trimmers such as the EGO Power+ ST1623T 16 in. String Trimmer Kit with 4.0Ah Battery and battery chainsaws such as the EGO Power+ CS1815 18 in. Chainsaw Kit with 6.0Ah Battery need no fuel at all.
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 ounces divided by 50 is 2.56. Many 2-stroke oils are sold in 2.6 ounce bottles for exactly this reason. For 2.5 gallons at 50:1, add 6.4 ounces, and for 5 gallons add 12.8 ounces.
What is the difference between 40:1 and 50:1 mix?
A 40:1 mix has more oil than 50:1: 3.2 ounces per gallon versus 2.6 ounces. The difference is about 25 percent more oil. Use the ratio your engine specifies. Running a 50:1 engine on 40:1 usually causes a little extra smoke and deposits, while running a 40:1 engine on 50:1 reduces lubrication, which is the riskier mistake.
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 ratio in the operator manual. If you have tools needing different ratios, keep separate, clearly labeled fuel cans or use the ratio specified for each tool.
How much oil for 5 liters of gas at 50:1?
For 5 liters of gasoline at 50:1, add 100 milliliters of 2-stroke oil, since 5,000 milliliters divided by 50 is 100. At 40:1 the same 5 liters needs 125 milliliters, and at 32:1 about 156 milliliters. A measuring cup marked in milliliters or a ratio bottle makes metric mixing easy.
Does 2-stroke oil brand 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 designed for water-cooled engines and are not a substitute for air-cooled outdoor power equipment unless the 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.