2 Stroke Oil Mix Calculator
Calculate the perfect fuel-to-oil ratio
Quick Reference Table
| Fuel | 50:1 | 40:1 | 32:1 |
|---|
How to Use This 2-Stroke Oil Mix Calculator
Using this tool is simple. It works as a quick fuel ratio converter for any 2-stroke engine:
- Enter the amount — Input how much gasoline you’re using (in US gallons or litres)
- Select your ratio — Choose from common options like 50:1, 40:1, 32:1, or 25:1
- Get your result — See exactly how many ounces of oil to add
The results display in fluid ounces, milliliters, and tablespoons — so you can measure with whatever you have on hand.
Understanding Two Stroke Oil Mix Ratios
A ratio tells you how much gasoline to combine with two-stroke lubricant. For example, a 50:1 (or 50-1) means 50 parts petrol to 1 part lubricant. The higher the first number, the less oil per gallon you’ll use.
Common Fuel to Oil Ratio Chart
| Ratio | Per Gallon of Gas | Per 5 Gallons | Best For |
|---|---|---|---|
| 50:1 | 2.6 oz | 12.8 oz | Modern outboard motors, most 2-cycle engines |
| 40:1 | 3.2 oz | 16 oz | Some chainsaws, older outboards |
| 32:1 | 4 oz | 20 oz | Older two stroke engines |
| 30:1 | 4.3 oz | 21.3 oz | Some vintage engines, specific equipment |
| 25:1 | 5.1 oz | 25.6 oz | Vintage engines, break-in periods |
| 100:1 | 1.3 oz | 6.4 oz | AMSOIL and some synthetic products |
Which Ratio Should You Use?
Always check your engine manual for the specific recommendation. Using too little oil causes engine damage due to insufficient lubrication, while too much leads to carbon buildup.
Most modern outboard engines use 50:1. However, premium synthetics like AMSOIL are designed for 100:1 — follow the manufacturer’s specs.
Quick Reference: How Much Oil You Need
- 1 gal = 2.6 oz
- 2 gal = 5.1 oz
- 5 gal = 12.8 oz
- 1 gal = 3.2 oz
- 2 gal = 6.4 oz
- 5 gal = 16 oz
- 1 gal = 4 oz
- 2 gal = 8 oz
- 5 gal = 20 oz
- 1 gal = 4.3 oz
- 2 gal = 8.5 oz
- 5 gal = 21.3 oz
Two Stroke Guide for Metric Users
If you measure in metric, simply toggle to “L” mode and enter your amount.
Metric Conversion Reference
- 1 US gallon = 3.785 litres
- 1 fl oz ≈ 29.6 ml
For a 50:1 with 1 L of petrol, you need approximately 20 ml of 2-stroke lubricant.
Fuel Ratios by Engine Type
Different 2-cycle engines may require different ratios:
Outboard Motors
- Modern two-stroke outboards: 50:1 (most common)
- Older carbureted models: 40:1 or 32:1
- Break-in period: Often 25:1 for the first few hours
Power Tools & Equipment
- Leaf blowers: Usually 40:1 or 50:1
- Chainsaws: 40:1 or 50:1 (check manual)
- String trimmers: 40:1 or 50:1
The Math Behind the Tool
Want to calculate manually? Here’s the formula:
Ounces = Gallons × 128 ÷ Ratio
Example for 1 gallon of gas at 50:1:
1 × 128 ÷ 50 = 2.56 oz
Tips for Proper 2-Stroke Oil Preparation
✓ Do’s
- Use fresh unleaded gasoline (less than 30 days old)
- Use quality 2-cycle engine oil rated TC-W3 for marine use
- Shake well before adding to your tank
- Measure the amount precisely
✗ Don’ts
- Never use regular motor oil
- Don’t guess the mixture amounts
- Avoid stale petrol
- Don’t store premix longer than 30 days
Frequently Asked Questions
What is the best 2 stroke oil ratio?
For most modern two-stroke engines, including outboard motors and power equipment, 50:1 is standard. This means 2.6 ounces per gallon. Always verify with your engine’s manual.
How do I prepare 50-1?
Add 2.6 fl oz of 2-stroke oil to every 1 gallon of gas. For 5 gallons, you need about 12.8 oz. Use the calculator above for precise measurements.
What happens with too little lubrication?
Insufficient lubrication causes increased friction, overheating, and potentially catastrophic engine damage. Two-stroke engines rely entirely on the oil mixture — there’s no separate reservoir.
Can I use any 2-cycle product?
For outboard engines, use TC-W3 rated marine products. For air-cooled equipment like chainsaws and leaf blowers, use products rated for air-cooled 2-cycle engines.
Disclaimer: Always refer to your engine manufacturer’s specifications for the correct ratios. This tool is provided for convenience and general reference only.