Power to Weight Ratio in Boats: The Formula for Speed on Water
Marine performance adds a new variable: water drag. Learn why power to weight ratio is critical for getting on plane and maximizing speed on the water.
Calculate performance metrics for cars, cycling, and weightlifting. Enter power and weight to instantly see 0-60 estimates, Watts/kg for cyclists, and legal checks for LAMS/P-Platers. Supports HP per ton, kW per tonne, and more.
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Input the power (HP, kW, Watts) and weight (kg, lbs). This works for cars, motorcycles (LAMS), and athletes (cycling FTP).
Choose your preferred units. The calculator automatically converts HP to kW or lbs to kg for accurate ratio comparison.
View results in standard formats like "HP per Ton" (for 0-60 estimates) or "Watts/kg" (for cycling performance).
Click any result card to set a target ratio (e.g., '150 kW/t' for LAMS compliance) and see how much power you need.
Why Power to Weight Ratio is the ultimate equalizer in performance.
At its core, acceleration is governed by Newton's Second Law: F = ma (Force equals Mass times Acceleration). Rearranging this formula gives us a = F / m.
This simple equation proves that to accelerate faster, you have two options: increase the FORCE (Power) or decrease the MASS (Weight). This is why a lightweight Lotus Elise with only 200hp can keep up with a heavy 400hp muscle car on a twisty track. The calculator above helps you quantify this relationship instantly.
When shopping for a car, horsepower numbers can be misleading. A heavy SUV with 300hp will feel much slower than a compact sedan with the same power. Use our benchmarks to find your sweet spot:
"Always check the curb weight, not just the engine power. A 200hp car weighing 1,000kg is significantly faster than a 300hp car weighing 1,800kg."
Adding horsepower is expensive. Reducing weight is often free.
Watts per Kilogram (W/kg) is the golden standard for climbing.
Compare your ratio against common vehicle classes. This chart helps estimate 0-60 mph times and checks against P-Plater/LAMS limits (130 kW/t).
| Vehicle Category | Power Ratio | Watts/kg | Est. 0-60 mph |
|---|---|---|---|
| Economy Car | 80 - 100 hp/ton | 60 - 75 W/kg | 10.0s + |
| P-Plate / LAMS Limit | ~174 hp/ton | 130 W/kg | 7.0s - 8.0s |
| Sporty Hatch | 180 - 220 hp/ton | 150 W/kg | 6.0s - 7.0s |
| Sports Car | 250 - 350 hp/ton | 220 W/kg | 4.0s - 5.5s |
| Supercar | 500 - 650 hp/ton | 400 W/kg | 2.8s - 3.5s |
| Formula 1 / Hypercar | 1000+ hp/ton | 750+ W/kg | < 2.5s |
FAQ
Marine performance adds a new variable: water drag. Learn why power to weight ratio is critical for getting on plane and maximizing speed on the water.
In the air and beyond, horsepower means nothing. It is all about Thrust to Weight. We explore how fighter jets defy gravity and how rockets escape it.
Electric cars have instant torque and massive horsepower, but they also have a weight problem. We explore the physics of EV performance.