Outboard 2-Cycle Fuel Mix Calculator & Marine Gas Oil Ratio Chart

Accurate 2-stroke oil ratios for boat fuel tanks: 50:1 modern outboards, 100:1 low-ratio models, and 24:1 / 25:1 vintage marine engines.

Important: Always use the ratio in your engine's owner's manual; oil-injected and 4-stroke outboards must not be premixed.

Gasoline Volume

Quick Tanks:

Measurement Unit

Target Ratio & Engine Type

Custom Ratio (Gas parts to 1 part oil)

Required TC-W3 Marine 2-Cycle Oil

15.36 fl oz

0.96 Pints (454.2 mL)

Why Marine 2-Stroke Outboards Need TC-W3 Certified Oil

Water-cooled marine outboards run much cooler than air-cooled engines. Always use NMMA TC-W3 certified marine 2-stroke oil. Air-cooled oils (JASO FD or ISO-L-EGD) will not burn cleanly in cold-running outboards, resulting in spark plug fouling and heavy combustion chamber deposits.

Outboard Marine Fuel Mix Chart (Standard Boat Fuel Tanks)

Standard measurements for common portable and built-in marine gas tanks using US gallons, fluid ounces, and pints/quarts (1 Pint = 16 fl oz, 1 Quart = 32 fl oz, 1 Gallon = 128 fl oz):

Outboard Ratio	1 US Gallon	3 Gallons (Skiff Tank)	6 Gallons (Standard Tank)	12 Gallons (Dual Tank)	18 Gallons (Built-in Tank)
50:1 (Standard)	2.56 fl oz (75.7 mL)	7.68 fl oz (227.1 mL)	15.36 fl oz (~1 Pint / 454.2 mL)	30.72 fl oz (~1 Quart / 908.5 mL)	46.08 fl oz (1.44 Quarts / 1.36 L)
100:1 (Lean Mix)	1.28 fl oz (37.9 mL)	3.84 fl oz (113.6 mL)	7.68 fl oz (227.1 mL)	15.36 fl oz (~1 Pint / 454.2 mL)	23.04 fl oz (0.72 Quarts / 681.4 mL)
32:1 (Break-In)	4.00 fl oz (118.3 mL)	12.00 fl oz (354.9 mL)	24.00 fl oz (1.5 Pints / 709.8 mL)	48.00 fl oz (1.5 Quarts / 1.42 L)	72.00 fl oz (2.25 Quarts / 2.13 L)
25:1 (Vintage)	5.12 fl oz (151.4 mL)	15.36 fl oz (~1 Pint / 454.2 mL)	30.72 fl oz (~1 Quart / 908.5 mL)	61.44 fl oz (~2 Quarts / 1.82 L)	92.16 fl oz (2.88 Quarts / 2.73 L)
24:1 (Some vintage)	5.33 fl oz (157.7 mL)	16.00 fl oz (Exactly 1 Pint)	32.00 fl oz (Exactly 1 Quart)	64.00 fl oz (Exactly 2 Quarts)	96.00 fl oz (Exactly 3 Quarts)

Metric Outboard Fuel Mix Chart (Liters)

Standard measurements for metric marine fuel volumes using Liters and Milliliters (1 Liter = 1,000 mL):

Fuel Ratio	5 Liters	10 Liters	20 Liters	25 Liters	50 Liters
50:1 (2.0%)	100 mL	200 mL	400 mL	500 mL	1,000 mL (1.0 L)
100:1 (1.0%)	50 mL	100 mL	200 mL	250 mL	500 mL (0.5 L)
32:1 (3.1%)	156.3 mL	312.5 mL	625 mL	781.3 mL	1,562.5 mL (1.56 L)
25:1 (4.0%)	200 mL	400 mL	800 mL	1,000 mL (1.0 L)	2,000 mL (2.0 L)
24:1 (4.2%)	208.3 mL	416.7 mL	833.3 mL	1,041.7 mL (1.04 L)	2,083.3 mL (2.08 L)

Marine Fuel Mixing and Fuel System Best Practices

Use certified TC-W3 marine two-stroke oil: Protect against cylinder corrosion from moisture and keep piston rings free of carbon in cool-running outboard cooling passages with genuine TC-W3 marine 2-cycle oil on Amazon.
Fuel storage between trips: Adding a marine fuel stabilizer on Amazon can help fuel stored between trips to keep fuel fresh in portable tanks.
Keep a graduated ratio measuring cup onboard: When refilling at a marina fuel dock, a dedicated graduated marine oil measuring container on Amazon eliminates guessing errors.
Inspect portable fuel tank primer bulbs and fuel lines: Sun exposure and ethanol dry out rubber fuel lines and primer bulbs. If your tank or fuel line is cracked or stiff, replace it with a portable boat fuel tank and line kit on Amazon.
Mix fuel before connecting to the outboard: Pour the TC-W3 oil into the portable tank before pumping fuel to ensure immediate, complete mixing. Rock or swirl the portable tank before connecting the fuel line quick-connector to your motor.

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