Small Utility (Mowers/Chippers)
Standard Motorcycle/Scooter
High-Performance (Sportbikes/Racing)
2-Stroke Engine
Note: This is an estimate. Actual HP varies by compression, RPM, and fuel system.
How to Convert CC to HP
Converting CC (Cubic Centimeters) to HP (Horsepower) is a common task for small engine owners, motorcyclists, and DIY mechanics. However, it is important to understand that there is no direct mathematical formula that works for every engine. CC measures the volume of the engine cylinders, while HP measures the power output.
The output depends heavily on the engine's efficiency, cooling system, and tuning. For example, a 1000cc engine in a tractor produces significantly less horsepower than a 1000cc engine in a MotoGP motorcycle because of how they are designed to deliver torque and operate at different RPM levels.
General Conversion Estimates
For most consumer-grade small engines (like those found in lawnmowers or pressure washers), a common rule of thumb is:
15cc to 25cc = 1 HP
For utility engines: CC / 20 = Estimated HP
For modern performance engines: CC / 10 = Estimated HP
Displacement (CC)
Utility HP (Approx)
Sport HP (Approx)
50cc
2 – 3 HP
5 – 8 HP
125cc
5 – 7 HP
10 – 15 HP
250cc
10 – 14 HP
25 – 40 HP
600cc
30 – 45 HP
80 – 120 HP
Why the Calculation Varies
The "CC to HP" relationship is influenced by several mechanical factors:
RPM (Revolutions Per Minute): Higher revving engines generally produce more horsepower from the same displacement.
Engine Cycle: 2-stroke engines often produce more power per CC than 4-stroke engines because they fire twice as often.
Aspiration: Turbocharged or supercharged engines will have a much higher HP-to-CC ratio than naturally aspirated ones.
Compression Ratio: Higher compression ratios usually result in higher thermal efficiency and more power.
function calculateHP() {
var cc = document.getElementById("engineDisplacement").value;
var type = document.getElementById("engineType").value;
var resultBox = document.getElementById("hpResultBox");
var display = document.getElementById("hpDisplay");
if (cc === "" || isNaN(cc) || cc <= 0) {
alert("Please enter a valid displacement in CC.");
return;
}
var displacement = parseFloat(cc);
var hp = 0;
// Logic based on general industry averages for engine types
if (type === "utility") {
// Small utility engines roughly 1 HP per 20-25cc
hp = displacement / 22;
} else if (type === "standard") {
// Standard road bikes roughly 1 HP per 15-17cc
hp = displacement / 16;
} else if (type === "performance") {
// High performance engines roughly 1 HP per 8-10cc
hp = displacement / 9;
} else if (type === "twostroke") {
// 2-Strokes are more efficient per CC, roughly 1 HP per 12-14cc
hp = displacement / 13;
}
display.innerHTML = "