Torque Calculator

What Is Torque?

Torque is the rotational equivalent of force–the twisting or turning effort applied around a pivot point or axis. When you tighten a bolt with a wrench, apply the brakes in a car, or spin a drill, you’re applying torque. Without torque, nothing rotates.

In physics and engineering, torque determines whether something will rotate and how fast. The amount of torque depends on two things: how hard you push (force) and how far from the pivot you push (distance). Push harder or push farther away, and the torque increases.

The SI unit of torque is the newton-meter (N⋅m). In automotive and mechanical fields, pound-feet (lb-ft) and pound-inches (lb-in) are also common. One newton-meter equals approximately 0.738 pound-feet.

Torque Formula

The basic torque equation is:

τ = F × d

Where:

• τ (tau) = torque (N⋅m or lb-ft)
• F = force applied (newtons or pounds)
• d = perpendicular distance from the pivot (meters or feet)

If the force isn’t applied perpendicular to the lever arm, multiply by the sine of the angle:

τ = F × d × sin(θ)

Where:

• θ (theta) = angle between the force direction and the lever arm

Example Calculations

Example 1: Tightening a bolt

• You apply 50 newtons of force to a wrench 0.2 meters from the bolt’s center
• τ = 50 × 0.2 = 10 N⋅m

Example 2: Car engine torque

• An engine produces 300 pounds of force at the crankshaft, 1 foot from the pivot
• τ = 300 × 1 = 300 lb-ft

Example 3: Force at an angle

• You push with 200 newtons on a crank 0.5 meters away, at a 60° angle
• τ = 200 × 0.5 × sin(60°) = 200 × 0.5 × 0.866 = 86.6 N⋅m

Torque Calculator

The calculator above converts torque between units and computes torque from force and distance. Enter any two known values, and it calculates the third. If you’re working with angled force, input the angle to get the perpendicular component.

Common Torque Units and Conversions

Quick conversions:

• 1 N⋅m ≈ 0.74 lb-ft
• 1 lb-ft ≈ 1.36 N⋅m
• 1 lb-in ÷ 12 ≈ lb-ft

Torque in Automotive Applications

Engine torque is a key performance metric. It measures the rotational force the engine produces at the crankshaft. A typical car engine might produce 150–250 N⋅m (110–185 lb-ft), while performance vehicles can exceed 400 N⋅m (295 lb-ft).

Why torque matters:

• Acceleration: High torque at low RPMs produces quick off-the-line acceleration. This is why electric vehicles, which deliver maximum torque instantly, feel fast from a standstill.
• Towing: A truck with 400 lb-ft of torque can pull heavier loads than one with 250 lb-ft. Torque capacity limits towing power.
• Grade climbing: Climbing hills requires sustained torque. More torque makes hills easier to climb at highway speeds.
• Gearing: Transmissions multiply engine torque through different gears, letting you apply more torque to the wheels at low speeds and maintain speed at high speeds.

Horsepower and torque work together. Torque determines how quickly you accelerate; horsepower determines how fast you can go. The relationship is:

Horsepower = (Torque in lb-ft × RPM) ÷ 5,252

At 3,000 RPM, an engine with 200 lb-ft of torque produces about 114 horsepower.

Torque in Machinery and Tools

Torque specifications are critical for many tasks:

• Tightening bolts: Socket wrenches with torque settings prevent over-tightening (which strips threads) or under-tightening (which causes failure). An engine block bolt might require 80 N⋅m; wheel bolts on a car typically need 100–150 N⋅m.
• Power drills: Drill ratings in N⋅m show how much rotational force they can deliver. A 50 N⋅m drill is stronger than a 20 N⋅m model.
• Impact wrenches: These deliver short, powerful torque pulses. A 400 N⋅m impact wrench can loosen stuck fasteners easily.
• Pumps and motors: Their torque ratings determine the load they can handle and the work they perform.

How to Use a Torque Wrench

A torque wrench ensures fasteners are tightened to specification:

1. Set the wrench to the required torque value by rotating the handle.
2. Attach the correct socket (usually 1/2" or 3/8" drive).
3. Position the fastener and apply force smoothly, not jerking.
4. Stop when you feel a click – most click-type wrenches signal when the target torque is reached.
5. Release the fastener and reset the wrench.

Using the correct torque prevents damage to engines, transmissions, suspension systems, and other critical components.

Torque Direction

Torque has direction. In physics, this is represented as a vector. Using the right-hand rule: curl your fingers in the direction of rotation, and your thumb points in the direction of the torque vector.

• Clockwise rotation is typically considered negative torque.
• Counterclockwise rotation is typically considered positive torque.

In practical work, you specify torque direction by the axis it rotates around (e.g., “rotate clockwise” or “apply counterclockwise force”).

When to Reach for the Torque Calculator

Use this calculator when you need to:

• Convert between torque units for international work or specifications
• Calculate required torque from known force and distance
• Find the force needed given a distance and target torque
• Determine the effective distance needed to apply a specific force and achieve a target torque
• Check automotive or machinery specifications in different unit systems