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Engine Horsepower Calculator | From Torque & RPM

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An engine horsepower calculator converts measured torque at a given engine speed into horsepower with the relationship HP = torque(lb-ft) × RPM ÷ 5,252. Because 5,252 is where torque and horsepower curves cross on a dyno chart, any RPM below it shows more torque than horsepower, and any RPM above shows more horsepower.

Last updated: September 2026 · Free · No sign-up required

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Results

Enter values above and click Calculate to see your result instantly.

Quick reference

Torque (lb-ft)RPMHorsepower
2003,000114
3005,252300
3506,500433
4007,000533

show_chart Read dyno charts

Torque and horsepower curves always intersect at 5,252 RPM — use it as a sanity check when reading dyno sheets.

electric_bolt Electric motors

EV motors make peak torque at 0 RPM, so their HP still rises with speed even as torque falls off.

build Towing vs speed

Torque does the lugging (towing, climbing); horsepower is how fast you can do work — high-RPM power.

swap_horiz Metric conversion

1 hp = 0.7457 kW = 1.014 PS. N·m converts to lb-ft by multiplying 0.7376.

lightbulb A real example — 350 lb-ft at 6,500 RPM

A twin-turbo V6 makes 350 lb-ft at 6,500 RPM on the dyno.

Result: 433 hp at that point (350 × 6,500 ÷ 5,252).

What this means: If the same engine held 350 lb-ft to 7,000 RPM it would make 466 hp — which is why turbo durability at high RPM matters more than the peak number.

Formula & methodology

Formula: HP = Torque(lb-ft) × RPM ÷ 5,252

Where 5,252 comes from

Horsepower is defined as 550 ft·lb/s. One revolution moves a torque arm 2π radians, so P = T × 2π × RPM ÷ 33,000, which simplifies to HP = T × RPM ÷ 5,252.

Example: 300 lb-ft at 5,252 RPM is exactly 300 HP. At 6,000 RPM it is 342 HP; at 3,000 RPM, 171 HP.

For metric units: kW = N·m × RPM ÷ 9,549, and 1 hp ≈ 0.7457 kW.

Frequently asked questions

How do you calculate horsepower from torque?
Multiply torque in lb-ft by RPM and divide by 5,252. For example, 300 lb-ft at 6,000 RPM makes 342 horsepower.
Why do horsepower and torque curves cross at 5,252 RPM?
Because HP = torque × RPM ÷ 5,252. When RPM equals 5,252 the equation reduces to HP = torque, so the two curves must intersect there on any consistent dyno chart.
How much horsepower is 400 lb-ft at 7,000 RPM?
400 × 7,000 ÷ 5,252 ≈ 533 hp.
Does more torque or more horsepower accelerate faster?
Acceleration at any instant follows wheel torque, but horsepower captures how long that torque can be sustained as speed rises — peak acceleration happens at peak power in the right gear.
How do I convert horsepower to kilowatts?
Multiply horsepower by 0.7457: 300 hp ≈ 224 kW. Going the other way, multiply kilowatts by 1.341. Much of the world rates engines in kW or PS (metric horsepower, where 1 PS = 0.986 hp), so a '150 PS' European hatchback is about 148 hp — close, but not identical, to 150 hp.
Is wheel horsepower the same as crank horsepower?
No. The calculator gives crank (flywheel) horsepower derived from engine torque, while a chassis dyno measures power at the wheels after drivetrain losses — roughly 10–15% for front-wheel drive and 15–20% for all-wheel drive. A car rated 300 hp at the crank typically puts down 255–270 hp at the wheels. Never compare a manufacturer's crank rating directly against a dyno sheet's wheel figure.
Can I calculate torque from horsepower instead?
Yes — rearrange the formula: torque (lb-ft) = HP × 5,252 ÷ RPM. A 400 hp engine at its 6,500 RPM power peak is making about 323 lb-ft at that point. The reversal is handy when a spec sheet lists only peak power and you want the torque figure behind it.
Why do diesel engines make big torque but modest horsepower?
Diesels rev low — peak torque often arrives by 1,500–2,000 RPM — and the formula multiplies torque by RPM, so low revs cap horsepower even when torque is huge. 500 lb-ft at 2,000 RPM is only 190 hp, while the same 500 lb-ft at 6,000 RPM would be 571 hp. This is also why diesel power bands feel narrow: the torque arrives early and the revs run out quickly.

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