Cc to Hp Converter

CC to HP Converter that turns displacement into likely horsepower for mowers, motorcycles, cars and diesel trucks. It also works in reverse, from horsepower back to an engine size.

CC to HP Converter for Mowers, Bikes, Cars and Diesels

Displacement measures how much air an engine can swallow per cycle, and horsepower measures how fast it turns that air into work. There is no fixed rate between the two, so the CC to HP converter works from the engine type you pick and the published ratings of real engines of that type.

It runs in both directions. Enter cc to get likely horsepower, or enter horsepower to see what size engine usually makes it. Displacement can be entered in cc, liters or cubic inches, and power in hp, kW or PS, with 1 L = 1,000 cc, 1 ci = 16.387 cc and 1 PS = 735.5 W.

Why the 15 cc Rule Gets Most Engines Wrong

Many online converters divide cc by 15 for every engine. That rule turns a 150 cc scooter into 10 hp and a 2,500 cc car engine into about 167 hp, whatever the engine is built for. Other converters use a different fixed number, such as 32.5 cc per hp, and give very different answers for the same engine.

A single number cannot work because engines of the same size are built for different jobs. The 212 cc engine on a mower or log splitter is governed to 3,600 RPM, while a 249 cc sport bike engine revs past 15,000. By the 15 cc rule both would make about 14 to 17 hp, but the real figures are about 6.5 hp and 43.5 hp.

The converter instead uses a cc-per-hp band for each engine type. The band runs from the lowest to the highest ratio among that type’s reference engines, and the estimate sits in the middle.

$$\text{hp} = \frac{\text{cc}}{\text{cc per hp}}$$

$$\text{cc} = \text{hp} \times \text{cc per hp}$$

The Engines Behind Each Band

Every band comes from published manufacturer ratings, which the third results table in the tool lists for the type you pick. The table below shows all of them together.

The spread between types is the whole story. The same 200 cc comes out near 6 hp as a mower engine and near 37 hp as a sport bike engine, a gap of about six times from displacement alone.

How Much Horsepower Is a 212cc Engine?

This is the size most people ask about, because of the Predator 212 sold by Harbor Freight. It is rated at 6.5 hp. With the Small Engine type selected, the converter estimates about 6.3 hp for 212 cc, within a likely range of 5.9 to 6.7 hp.

Real dyno pulls land in that range. EC Carburetors reports stock Predator 212 runs of 6.24 and 6.39 hp after the dyno was recalibrated, with a best stock run of 6.74 hp in a later test.

The small-engine band uses Honda’s GX series because Honda states how it rates them. Its GX brochure gives SAE J1349 net power at 3,600 RPM, measured with the production muffler and air cleaner fitted. The GX200 makes 5.5 hp from 196 cc on that basis.

Published torque figures on small engines do not always agree with the horsepower. A Snowblower Forum member noted that the Predator’s listed 8.1 lb-ft at 2,500 RPM works out to under 6 hp even at 3,800 RPM. The horsepower rating is the better number to go by.

bhp, PS and kW on Spec Sheets

Indian and European spec sheets often print bhp or PS, and those are not always mechanical horsepower. Royal Enfield’s Classic 350 spec sheet lists 20.2 bhp at 6,100 RPM alongside 14.87 kW, and 14.87 kW works out to 19.9 mechanical hp.

That matches a metric horsepower of 735.5 W, about 1.4% smaller than the 745.7 W mechanical horsepower. The fourth result card shows every answer in kW, PS and watts so a figure from any market can be compared directly.

Turning Horsepower Back Into Displacement

Type in the Horsepower box and the converter works the other way, returning the likely engine size for that power. A 6.5 hp small engine comes out at about 219 cc, with a likely range of 206 to 232 cc, which brackets the 212 cc Predator.

The same 6.5 hp would need only about 35 cc in a sport bike engine and about 115 cc in an air-cooled single. The second table in the tool lays out every type side by side for the power you enter.

Where a CC to HP Converter Stops Being Useful

Boost stretches the turbo band more than any other. Volkswagen’s 2.0-liter turbo makes 241 hp in the US Golf GTI and 328 hp in the Golf R, according to MotorWeek, so displacement alone can only narrow a turbo engine to a range.

Diesels look weak by this measure because they make their power as torque. The 430 hp Cummins 6.7 in the 2025 Ram Heavy Duty also makes 1,075 lb-ft, far more pulling force than a gas engine rated at the same horsepower.

None of the six types covers two-stroke engines, which make more power per cc than a four-stroke of the same size. Displacement is accepted from 10 to 20,000 cc and power from 0.5 to 2,000 hp. When an entry falls well outside the sizes behind the chosen type, the tool flags the result as a rough guide.

Quick Answers for Common Engine Sizes

How much horsepower is a 150cc engine?

It depends on what the engine is built for. As an air-cooled single like a commuter bike or scooter, 150 cc comes out near 8.4 hp, within a range of 8.3 to 8.6 hp. The 15 cc rule would say 10 hp.

The same 150 cc as a governed small engine would make only about 4.5 hp. As a high-revving sport bike engine it would make about 28 hp, which shows why picking the right engine type matters more than the displacement itself.

Does one cubic inch equal one horsepower?

That old rule is close for naturally aspirated car engines and far off for everything else. The Chevrolet LT1 crate engine makes 460 hp from 376 cubic inches, per Engine Labs, which is about 1.2 hp per cubic inch.

A Honda GX200 makes 5.5 hp from 12 cubic inches, closer to 0.5 hp per cubic inch. Set the Units menu to Cubic Inches and hp to see the converter’s answer in those terms for any engine type.