When it comes to small engines—like those found in lawn mowers, motorcycles, go-karts, and generators—you often hear two units of measurement: cubic centimeters (CC) and horsepower (HP).
While these two terms measure different things, they’re related. CC measures the engine size (displacement), while HP measures the power output of the engine.
Calculator
- Enter the CC value and the conversion factor (default value 15 although it typically varies between 15 and 17).
- The tool will calculate the equivalent HP value.
Background
If you need to convert CC to HP for small engines, this guide includes explanation as well as some key factors to consider and rough estimation methods.
What is CC?
Cubic centimeters (CC) refers to the total volume of the engine’s cylinders, which determines how much air and fuel the engine can draw in.
- Higher CC generally means a bigger engine with more capacity to produce power.
- Lower CC engines are smaller and usually produce less power, but they are often more fuel-efficient.
For example, a 200cc engine has cylinders with a combined volume of 200 cubic centimeters.
What is HP?
Horsepower (HP) measures the engine’s power output—the amount of work it can do in a certain amount of time. One horsepower is roughly equivalent to the amount of power needed to move 550 pounds one foot in one second.
In small engines, higher horsepower usually means the engine can perform heavier tasks, such as cutting thick grass, moving a go-kart quickly, or powering heavy equipment.
How to Convert CC to HP for Small Engines
There is no exact formula for converting CC to HP because many variables affect how much horsepower an engine produces, such as:
- Engine efficiency
- Fuel type
- Compression ratio
- Design (two-stroke or four-stroke engine)
However, there are rough estimates based on typical small engine performance.
CC to HP Conversion Estimate
15 to 17 CC = 1 HP
This means that for every 15 to 17 cubic centimeters of displacement, the engine produces approximately 1 horsepower.
This is the conversion factor in the calculator above.
Quick CC to HP Conversion Table (Approximate)
| Engine Size (CC) | Estimated HP |
|---|---|
| 50 CC | 3 to 3.5 HP |
| 100 CC | 6 to 7 HP |
| 150 CC | 9 to 10 HP |
| 200 CC | 11 to 13 HP |
| 250 CC | 15 to 17 HP |
| 300 CC | 18 to 20 HP |
Example Conversions
A 200 CC engine:
200 ÷ 15 = 13.3 HP (approximately)
A 100 CC engine:
100 ÷ 16 = 6.25 HP (approximately)
These values are estimates. The actual horsepower can vary based on engine efficiency, design, and other factors.
Two-Stroke vs. Four-Stroke Engines
Another important factor in converting CC to HP is whether the engine is two-stroke or four-stroke.
Two-stroke engines produce more power per CC but are less fuel-efficient.
Four-stroke engines generate less power per CC but are more fuel-efficient and quieter.
For example, a 50 CC two-stroke engine may produce 5 HP, while a 50 CC four-stroke engine might only produce 3 HP.
Why You Might Need CC to HP Conversion
Knowing the approximate HP of an engine is helpful in several situations:
- Comparing engines when shopping for small engines or equipment
- Choosing the right engine with enough power for tasks like mowing thick grass
- Anticipating performance improvements when modifying or tuning engines (e.g., go-karts)
Limitations of CC to HP Conversion
While the CC to HP ratio can give you a rough idea of engine power, it’s not always accurate. Two engines with the same CC rating may have different HP outputs due to:
- Engine quality and tuning
- Fuel type (gasoline, diesel, or ethanol blends)
- Environmental factors (elevation, temperature)
Whenever possible, check the manufacturer’s specifications for the exact HP rating.
Conclusion
Converting CC to HP for small engines gives you a rough idea of the engine’s power. While there’s no exact formula, a general rule of thumb is that 15 to 17 CC equals 1 HP. However, factors like engine type (two-stroke vs. four-stroke), fuel efficiency, and tuning can affect the actual output.
Use this conversion as a starting point to make informed decisions when buying or comparing small engines, whether for lawn equipment, motorcycles, or go-karts. Also refer to the manufacturer’s specifications for the exact horsepower rating.