Type how much gas you are mixing and the ratio your machine asks for. The oil comes out below in ounces and millilitres, with the whole ratio as a chart you can print for the shed wall — and what STIHL, Husqvarna and ECHO each publish for their own equipment.
1 gal of gas at 50:1
Add 2.6 fl oz of oilThat is 76 ml. About one standard 2.6 fl oz bottle.
- Oil
- 2.6 fl oz (76 ml)
- Gas
- 1 gal (3.79 L)
- In the can when mixed
- 1.02 gal
- Oil by volume
- 1.96%
| Gas | Oil | Oil, the other way |
|---|
The manual on your own saw or trimmer outranks this page, and it is the only thing that knows which ratio your engine was built for. Mix outdoors, keep it off your skin, and mix only what you will burn — a can of two-cycle mix does not keep.
Oil standard and fuel notes checked 2026-09-24.
Quick answer: at 50:1 — what almost every modern chainsaw, trimmer and blower asks for — one US gallon of gas takes 2.6 fl oz (76 ml) of two-cycle oil, and 2½ gallons take 6.4 fl oz. At 40:1 a gallon takes 3.2 fl oz, at 32:1 it takes 4 fl oz. STIHL says plainly that “all STIHL gasoline-powered equipment uses a 50:1 gas and oil mixture”. Husqvarna publishes two figures — 50:1 (2%) with their own oil, 33:1 (3%) with anybody else’s — which is the line almost nobody else prints.
How to use it
Pick the ratio your manual asks for, type how much gas you are about to mix, and read the oil figure. It comes out in both fluid ounces and millilitres, because the jug on the shelf and the bottle in your hand rarely agree on which one they use. If you have already emptied a bottle into the can and lost count, switch to The oil I poured and it tells you how much gas that oil is mixed for instead.
Choosing a maker shows you what that company publishes, in its own words, with a button to use its ratio. It does not pick a ratio for your machine, because this page cannot see your machine — and on a two-stroke, too little oil is the mistake that ends with a seized piston.
The mix chart, at a glance
| Ratio | Per US gallon | Per 2½ US gallons | Per liter | Per 5 liters |
|---|---|---|---|---|
| 50:1 | 2.6 fl oz | 6.4 fl oz | 20 ml | 100 ml |
| 40:1 | 3.2 fl oz | 8 fl oz | 25 ml | 125 ml |
| 33:1 | 3.9 fl oz | 9.7 fl oz | 30 ml | 152 ml |
| 32:1 | 4 fl oz | 10 fl oz | 31 ml | 156 ml |
| 25:1 | 5.1 fl oz | 12.8 fl oz | 40 ml | 200 ml |
| 16:1 | 8 fl oz | 20 fl oz | 63 ml | 313 ml |
Those are the calculator’s own numbers, rounded the same way. The ratio is gas to oil by volume, so the oil goes on top of that much gas rather than being part of it — the difference is small, and this page says which it means rather than leaving you to guess.
What each maker actually says
STIHL is the simplest: 50:1 across the range, with mid-grade gas. Their own words — “Mid-grade unleaded gasoline with a minimum octane rating of 89 is recommended for your mixture. Fuel with a lower octane rating may increase engine temperatures, increasing the risk of piston seizure and damage to the engine.” Pour the oil into the can first, add the gas, and shake it.
Husqvarna publishes the distinction that catches people out: “The recommended ratio between gasoline and two-stroke oil is 50:1 (2%) for original Husqvarna 2-stroke oil. If other branded 2-stroke oil is used, the recommended ratio is 33:1 (3%).” If you are running a generic bottle from the hardware store in a Husqvarna, their own guidance is a richer mix, not the 50:1 on the fuel cap. They also warn that “small errors can influence the ratio of the mixture drastically when you mix small quantities of fuel” — which is why mixing half a gallon by eye is a bad habit.
ECHO sells both the oil and the finished fuel, pre-mixed at 50:1 and ethanol-free, and says its universal PowerBlend oil can run at 50:1 in every ECHO engine it has sold, whatever ratio the old manual gives. That is a claim about ECHO oil in ECHO engines — it is not permission to lean out somebody else’s saw.
Which oil, and why the marine bottle is the wrong one
Two-cycle oil is not one product. A chainsaw or trimmer is air-cooled and runs far hotter than an outboard, which is water-cooled. The oil made for outboards is certified to the NMMA’s TC-W3 standard — tests for fluidity, for mixing properly with fuel, for rust, and for carbon and ring-sticking in a marine engine. It is a different formulation from the oil the handheld makers specify, it is usually cheaper, and it sits on the same shelf. Buy the oil your machine’s maker names.
The reverse is just as true, and it is the mistake a boat owner makes in the garden: air-cooled oil is not certified for an outboard. If you have both, label the cans.
Mixed fuel does not keep
STIHL’s instruction is to “only mix sufficient fuel for a few days’ work” and that “fuel storage should never exceed three months”, shaking the can before each use. Two things are aging at once: the gas itself, which is mostly E10 and pulls water out of the air, and the mix, which separates as it stands. Mix a gallon in the spring for a job that takes an afternoon and the last half of it is a hard-starting saw in July. If you want fuel that keeps, the ethanol-free canned pre-mix the makers sell is exactly what it is for — and if you want to know how old is too old for the can you already have, the gas shelf-life calculator takes it apart.
The mistakes that cost an engine
- Straight gas in a two-stroke. No oil means no lubrication at all, and a seizure inside a tank. If you ever fill a two-stroke from the mower can by mistake, stop before you start it and drain it.
- Guessing “about a capful”. Caps are not a unit. Measure it — Husqvarna’s own warning is about exactly this.
- Mixing in the machine’s tank. Oil and gas need agitating to blend, which a tank on a machine does not get. Mix in the can.
- Using four-stroke engine oil. It is not designed to burn, and it will coke up the exhaust port and the plug.
- Running last season’s mix “to use it up”. That is the tank that gums the carburettor.