How Much 2-Stroke Oil for 1 Gallon of Gas?
At 50:1, add 2.6 fl oz (76 mL) of 2-stroke oil.
At 40:1, add 3.2 fl oz (95 mL).
At 32:1, add 4 fl oz (118 mL).
Not sure which ratio? Use the one in your owner's manual or on the fuel cap. Most modern handheld equipment is 50:1. Other amounts: open the calculator.
One gallon is the usual batch for homeowners running a chainsaw, string trimmer or leaf blower. It is small enough to use up before the fuel goes stale, and it is the amount most single-mix oil bottles are sized for.
Oil for 1 Gallon at Every Ratio
| Ratio | Oil (fl oz) | Oil (mL) | Easy measure | Typically used for |
|---|---|---|---|---|
| 50:1 | 2.6 fl oz | 76 mL | one 2.6 oz pre-measured 50:1 bottle, or about 5 tablespoons | Modern chainsaws, trimmers, blowers; most modern outboards |
| 40:1 | 3.2 fl oz | 95 mL | one 3.2 oz pre-measured 40:1 bottle, or about 6.5 tablespoons | Older equipment, some trimmers and outboards, many dirt bikes |
| 32:1 | 4 fl oz | 118 mL | about 8 tablespoons | Dirt bikes and motocross, high-load engines |
| 30:1 | 4.3 fl oz | 126 mL | about 8.5 tablespoons | Vintage outboards |
| 25:1 | 5.1 fl oz | 151 mL | about 10 tablespoons | Older equipment, break-in when specified |
| 20:1 | 6.4 fl oz | 189 mL | about 13 tablespoons | Vintage engines, some racing |
| 16:1 | 8 fl oz | 237 mL | about 16 tablespoons | Antique engines and outboards |
1 gallon is 3.79 liters. These amounts are for US gallons. If your manual uses UK (imperial) gallons, which are about 20% larger, 1 imperial gallon at 50:1 needs 91 mL of oil.
How Precise Do You Need to Be?
Staying within about 10% of the target amount keeps you close to the intended ratio. For 1 gallon at 50:1 that means 2.3–2.8 fl oz of oil, and at 40:1, 2.9–3.5 fl oz.
At this batch size, an extra 1 fl oz of oil turns a 50:1 mix into about 36:1, and 1 fl oz too little makes it about 82.1:1. Running slightly rich (more oil) is safer for the engine than running lean.
Mixed 1 Gallon at the Wrong Ratio?
You don't need to throw it out. To correct a full 1-gallon batch:
| Situation | Fix |
|---|---|
| Mixed 40:1, need 50:1 | Add 0.25 gallons of fresh gas (1.25 gallons total) |
| Mixed 50:1, need 40:1 | Add 0.6 fl oz more oil |
| Mixed 50:1, need 32:1 | Add 1.4 fl oz more oil |
| Mixed 32:1, need 50:1 | Add 0.56 gallons of fresh gas (1.56 gallons total) |
Adding gas makes the batch bigger, so only lean out a mix if you will use the extra fuel within about a month.
How to Mix 1 Gallon
- Measure the oil, for example 2.6 fl oz (76 mL) for 50:1. A ratio measuring cup reads directly in ounces and mL.
- A 1-gallon can, or a mixing bottle with ratio markings, keeps small batches accurate.
- Cap it tightly and shake for about 30 seconds. A fuel can with a sealing cap prevents spills while you shake.
- Write the ratio and date on the can. Shake again before each refill if the can has been sitting.
1 Gallon: Common Questions
How much oil for 1 gallon of gas at 50:1?
1 gallon at 50:1 needs 2.6 fl oz (76 mL) of 2-stroke oil.
How much oil for 1 gallon of gas at 40:1?
1 gallon at 40:1 needs 3.2 fl oz (95 mL) of 2-stroke oil.
How much oil for 1 gallon of gas at 32:1?
1 gallon at 32:1 needs 4 fl oz (118 mL) of 2-stroke oil.
I mixed 1 gallon at 40:1 but my engine needs 50:1. What do I do?
Add 0.25 gallons of fresh gas (1.25 gallons total). That brings the batch back to 50:1 without wasting it.
How long does 1 gallon of mixed fuel last?
Mixed 2-stroke fuel without stabilizer is best used within about 30 days. A fuel stabilizer extends that; follow the storage time on the stabilizer's label.
Other Fuel Amounts
Need a ratio guide instead? See 50:1, 40:1, 32:1 or all ratios.