horsepower torque calculator

What this horsepower torque calculator does

This horsepower and torque calculator helps you quickly convert between power, torque, and engine speed without doing manual math each time. It is useful for car enthusiasts, racers, mechanics, dyno chart readers, and anyone comparing engine setups.

If you've ever asked questions like “how much torque makes 400 hp at 6,500 RPM?” or “what RPM do I need to hit my target horsepower?” this tool gives you immediate answers.

Horsepower vs torque: what’s the difference?

Torque (lb-ft)

Torque is rotational force. In an engine, torque describes how strongly the crankshaft is being twisted. More torque at low RPM usually means stronger pull from a stop and better towing feel.

Horsepower (hp)

Horsepower is a measure of work over time. It combines torque and RPM into a single performance number. High horsepower usually translates to stronger acceleration at speed and better top-end performance.

Why both matter

Torque tells you “how hard” the engine is pushing. Horsepower tells you “how fast” that work is being done. A well-balanced engine setup considers both, along with gearing and vehicle weight.

The core formula used in this calculator

For torque in pound-feet and speed in revolutions per minute:

• Horsepower = (Torque × RPM) ÷ 5252
• Torque = (Horsepower × 5252) ÷ RPM
• RPM = (Horsepower × 5252) ÷ Torque

The constant 5252 comes from unit conversion in imperial units. It’s also why horsepower and torque values are numerically equal at 5,252 RPM on an hp/lb-ft dyno plot.

How to use the calculator

• Select what you want to calculate: horsepower, torque, or RPM.
• Enter the other two known values.
• Click Calculate to get your answer instantly.
• Use Reset to clear all fields and start over.

Tip: Keep units consistent. This page assumes torque is entered in lb-ft, not N·m.

Practical examples

Example 1: Find horsepower

If torque is 350 lb-ft at 5,500 RPM:

HP = (350 × 5500) ÷ 5252 = 366.53 hp

Example 2: Find torque

If an engine makes 450 hp at 6,200 RPM:

Torque = (450 × 5252) ÷ 6200 = 381.44 lb-ft

Example 3: Find required RPM

If torque is 300 lb-ft and you want 400 hp:

RPM = (400 × 5252) ÷ 300 = 7002.67 RPM

Common mistakes to avoid

• Mixing units (N·m and lb-ft) without conversion.
• Using peak torque with peak horsepower RPM as if they happen at the same point.
• Ignoring drivetrain losses when comparing engine dyno vs wheel dyno numbers.
• Rounding too early during calculations.

Related calculations people also search for

• hp to torque conversion calculator
• engine RPM calculator
• wheel horsepower vs crank horsepower calculator
• quarter mile power-to-weight estimator
• kW to hp converter

Final thoughts

A good horsepower torque calculator should be simple, accurate, and fast. This one is built around the standard drivetrain formula used by enthusiasts and professionals. Use it to compare build options, understand dyno graphs, and estimate performance targets with confidence.