2-Cycle Oil Mix Calculator: Ratios and Charts for 50:1, 40:1 and More
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Key Takeaways
- A 50:1 mix needs 2.56 fluid ounces of oil per U.S. gallon of gas. Most brands round it to 2.6 ounces.
- 50:1 is the most common ratio, but not the only one. Some Craftsman, Poulan Pro and Remington models call for 40:1.
- Husqvarna says to use 33:1 if you mix with another brand’s oil instead of Husqvarna oil.
- ECHO and Makita require 2-stroke oil rated JASO FD or ISO-L-EGD, and say other oils can void the warranty.
- Use mixed fuel within 30 days. STIHL allows up to 60 days but prefers 30.
A 2-stroke engine gets all of its lubrication from the oil you mix into the gas. Get the ratio wrong, and you can damage the engine.
Use the 2-cycle oil mix calculator below to get the exact amount of oil for any ratio. It works in U.S. gallons, UK gallons and liters.
Then check our charts and the ratio each brand actually requires. You might be surprised: not every engine runs on 50:1.
2-Cycle Oil Mix Calculator
Based on NIST unit definitions. Always use the ratio in your owner’s manual.
How to Calculate a 2-Stroke Oil Mix Ratio
The math is simple. Divide the amount of gas by the first number in the ratio.
A 50:1 ratio means 50 parts gas to 1 part oil. So for one gallon at 50:1, you need 1/50 of a gallon of oil.
A U.S. gallon is exactly 128 fluid ounces. That gives you 128 ÷ 50 = 2.56 ounces of oil per gallon.
In metric, it’s even easier. A liter is 1,000 mL, so 50:1 needs 1,000 ÷ 50 = 20 mL of oil per liter.
2-Stroke Mix Ratio Charts
Need a quick number? Use these charts. We calculated each value from the NIST unit definitions and rounded to one decimal place.
Mix Ratio Chart in U.S. Gallons
| Gas | 100:1 | 50:1 | 40:1 | 33:1 | 32:1 | 25:1 |
|---|---|---|---|---|---|---|
| 1 gal | 1.3 oz | 2.6 oz | 3.2 oz | 3.9 oz | 4.0 oz | 5.1 oz |
| 2 gal | 2.6 oz | 5.1 oz | 6.4 oz | 7.8 oz | 8.0 oz | 10.2 oz |
| 2.5 gal | 3.2 oz | 6.4 oz | 8.0 oz | 9.7 oz | 10.0 oz | 12.8 oz |
| 5 gal | 6.4 oz | 12.8 oz | 16.0 oz | 19.4 oz | 20.0 oz | 25.6 oz |
Mix Ratio Chart in Liters and UK Gallons
| Gas | 100:1 | 50:1 | 40:1 | 33:1 | 32:1 | 25:1 |
|---|---|---|---|---|---|---|
| 1 L | 10 mL | 20 mL | 25 mL | 30 mL | 31 mL | 40 mL |
| 5 L | 50 mL | 100 mL | 125 mL | 152 mL | 156 mL | 200 mL |
| 10 L | 100 mL | 200 mL | 250 mL | 303 mL | 313 mL | 400 mL |
| 1 UK gal | 45 mL | 91 mL | 114 mL | 138 mL | 142 mL | 182 mL |
What Mix Ratio Does Your Equipment Need?
Most modern handheld equipment uses 50:1. But some brands and models use 40:1 or even 33:1.
Using the wrong ratio means less oil than the engine was built for. So we checked the owner’s manuals and support pages of 14 brands.
| Brand | Mix ratio | Oil required | Min octane | Use mixed fuel within |
|---|---|---|---|---|
| STIHL | 50:1 | STIHL 2-stroke oil. No marine oil. | 89 | 60 days, ideally 30 |
| Husqvarna | 50:1 with Husqvarna oil, 33:1 with other brands | Husqvarna 2-stroke oil. No marine oil. | 87 | About 1 month, or 12 with stabilizer |
| ECHO | 50:1 | ISO-L-EGD and JASO FD | 89 | Gas bought within 30 days |
| Ryobi (gas) | 50:1 | Ethanol Shield or a quality synthetic oil. No outboard oil. | 87 | 30 days |
| Homelite | 50:1 | Ethanol Shield or Homelite premium oil. No outboard oil. | 87 | 30 days |
| Poulan Pro | 50:1 newer models, 40:1 some older models | Air-cooled 2-cycle oil. No automotive or marine oil. | 87 | Not listed |
| Craftsman (CMXGTAMD25CC) | 40:1 | Supplied oil or air-cooled 2-cycle oil | Not listed | Fuel under 30 days old |
| Makita (EA6100P) | 50:1 | JASO FD or ISO-L-EGD | 89 | 6–8 weeks in hot weather |
| Tanaka | 50:1 | Tanaka oil, or JASO FC / ISO-L-EGC | 89 | Not listed |
| Shindaiwa | 50:1 | ISO-L-EGD / JASO FD | 89 | Stabilize if over 30 days |
| RedMax | 50:1 | ISO-L-EGD and JASO FD | 89 | Not listed |
| Toro (2-cycle snowthrowers) | 50:1 | Toro oil or NMMA TC-W certified oil | 87 | 30 days |
| Remington (RM2510) | 40:1 | Not confirmed | Not confirmed | Not confirmed |
| Dolmar (older saws) | 50:1 with Dolmar oil, otherwise 40:1 | Dolmar 2-stroke oil | Not listed | Not listed |
Using a Husqvarna? Husqvarna’s support page says to mix at 50:1 with its own oil, but at 33:1 with any other brand. Mixing a generic oil at 50:1 gives the engine about a third less oil than Husqvarna wants.
Why Did Older Engines Use 32:1 or 16:1?
Older 2-stroke oils needed a higher concentration to protect the engine. That’s why older manuals list ratios like 32:1 or 16:1.
ECHO says better oil technology now lets its engines run at 50:1. If your manual lists a richer ratio, though, follow it. That engine was built for it.
What 2-Stroke Oil Should You Use?
Use the oil rating your manual asks for. For most air-cooled equipment, that means JASO FD or ISO-L-EGD.
Two-stroke oils are rated under two similar systems: Japan’s JASO M345 and the international ISO 13738. Both test how well the oil lubricates, keeps the engine clean and limits smoke and exhaust buildup, according to oil maker Rymax.
| JASO rating | ISO rating | What it means |
|---|---|---|
| FA | None | The original basic grade. No longer used. |
| FB | ISO-L-EGB | A step up from FA. |
| FC | ISO-L-EGC | Same lubrication as FB, with tighter limits on deposits, smoke and exhaust buildup. |
| FD | ISO-L-EGD | Same as FC, but with higher cleaning (detergency) standards. ISO-L-EGD also has the strictest piston cleanliness test. |
The rating matters for your warranty. ECHO says engine problems from using oil without ISO-L-EGD and JASO FD certification will void the warranty. Makita’s manual says the same.
Look for the rating printed on the bottle. Your engine maker’s own branded oil always meets its requirement.
Can You Use TC-W3 Marine Oil in a Chainsaw?
Usually not. TC-W3 is a certification for oils made for water-cooled boat engines.
Husqvarna says never to use oil meant for water-cooled engines in an air-cooled engine. Poulan says marine oils lack the right additives for air-cooled 2-cycle engines.
There’s one exception. Toro’s 2-cycle snowthrower manuals call for Toro oil or TC-W certified oil. As always, your manual decides.
What Happens If You Use the Wrong Mix Ratio?
Too little oil can destroy an engine. Too much oil causes smoke and carbon buildup.
| Too little oil (lean mix) | Too much oil (rich mix) | |
|---|---|---|
| What happens | Overheating and internal damage. Husqvarna warns of piston seizure. | Hard starting, rough running, smoke and carbon buildup. Makita adds clogged exhaust ports and mufflers. |
| Warning signs | Often none until damage is done. | Visible smoke, oily residue, fouled spark plug. |
| Can it be fixed? | Scoring or seizure usually means a major repair. | Usually. Drain, remix, clean the carbon and replace the plug. |
Adding “a little extra oil to be safe” isn’t safe either. It just swaps one problem for another.
How to Mix 2-Cycle Fuel
Follow these steps every time you mix a new can.
1. Check the Ratio and Oil Rating
Find both in your owner’s manual. Treat the table above as a starting point only.
2. Use Fresh Gas
Most brands want 87 to 89 octane, and none allows more than 10% ethanol. Read our ethanol-free gas article to learn why you should never use E15.
3. Measure the Oil Exactly
Use the calculator above and a marked mixing bottle. Don’t guess.
4. Mix in an Approved Gas Can
Add the oil and gas to the can, close it and shake well. STIHL’s mixing instructions walk through the same process. Label the can as 2-stroke mix.
5. Shake Before Each Refill and Date the Can
Use the mix within 30 days unless your manual allows longer, or add a fuel stabilizer.
2-Stroke Oils and Mixing Bottles That Meet These Specs
If your manual calls for JASO FD or ISO-L-EGD oil, these products list that rating on the maker’s own page.
| Product | Why it fits | Where to buy |
|---|---|---|
| ECHO Red Armor 2-Stroke Oil (6550025) | ECHO says it exceeds ISO-L-EGD and JASO FD, and it includes fuel stabilizer. | Check price on Amazon |
| Husqvarna XP+ 2-Stroke Oil (593152303) | Husqvarna lists it as JASO FD certified. Use it at 50:1 in Husqvarna equipment. | Check price on Amazon |
| Seachoice 2-Cycle Measuring Bottle (50-21000) | Marked for 100:1, 50:1, 40:1 and 24:1 in gallons and liters. | Check price on Amazon |
| TruFuel 50:1 Premix (6525638) | Skips mixing entirely. Ethanol-free, made with JASO FD registered oil. | Check price on Amazon |
FAQs
How many ounces of oil per gallon for 50:1?
2.56 fluid ounces, usually rounded to 2.6. That’s 6.4 ounces for 2.5 gallons and 12.8 ounces for 5 gallons.
How much oil per gallon for 40:1?
3.2 fluid ounces per U.S. gallon, or 25 mL per liter.
Can I use 50:1 in an engine that calls for 40:1?
It’s not a good idea. 50:1 has 20% less oil than 40:1, so the engine gets less lubrication than it was built for.
Why does my UK chart show a different amount per gallon?
A UK gallon is about 20% bigger than a U.S. gallon. At 50:1, it needs about 91 mL of oil instead of 76 mL.
Is 2-cycle the same as 2-stroke?
Yes. Both terms mean the same type of engine, and you’ll see both on oil bottles and in manuals.
Conclusion
For most modern 2-stroke tools, the answer is 50:1, or 2.6 ounces of oil per gallon. But don’t assume.
Some brands and models use 40:1. Husqvarna changes the ratio based on which oil you use. And the oil rating matters as much as the ratio.
Check your manual, measure with the calculator above, and use your mix within 30 days.
Wondering which gas to mix with? Read our article on ethanol-free gas for small engines.
Sources
- National Institute of Standards and Technology. NIST Handbook 44 (2024), Appendix C: General Tables of Units of Measurement.
- STIHL. Fuel FAQ and Mixing oil and gasoline.
- Husqvarna. Ratio of fuel mix, How to mix 2-stroke fuel and support article KA-01557.
- ECHO. Fuel/Oil requirements. The 50:1 ratio and note on older ratios come from an ECHO support article we checked through search excerpts; it’s no longer online.
- Ryobi. RY252CS / RY253SS operator’s manual.
- Homelite. UT33600 operator’s manual.
- Poulan Pro. PP4218AV instruction manual (manual site copy). The 50:1 figure for the newer PR4218 comes from a manual copy on manualowl.com.
- Craftsman (MTD). CMXGTAMD25CC operator’s manual.
- Makita. EA6100P instruction manual.
- Manual copies on third-party sites: Tanaka TBC-290, Shindaiwa M242, RedMax CHT2301, Toro 38172, Remington RM2510 (not confirmed with an official source), Dolmar PS-34.
- Toro. Fuel facts.
- Rymax Lubricants. What does the JASO oil specification mean? (oil manufacturer).
- OilSpecifications.org. ISO 13738 two-stroke oil classification.
- National Marine Manufacturers Association. Oil certification (TC-W3).