How many foot-pounds are in one kilojoule?

One kilojoule equals 737.562 foot-pounds (ft·lbf). Conversely, 1 ft·lbf = 0.00135582 kJ (1.35582 J).

What is a foot-pound (ft·lbf)?

A foot-pound is a unit of energy (or work) in the imperial system. It equals the energy transferred when a one-pound force acts through a displacement of one foot. In the US it is also used for torque, but the unit size is the same as the energy foot-pound.

How do I convert kJ to ft·lbf manually?

Multiply your kJ value by 737.562 to get ft·lbf. For example, 1 kJ = 737.562 ft·lbf. To go the other way, multiply ft·lbf by 0.00135582 to get kJ.

Is foot-pound the same as pound-foot?

The terms foot-pound (ft·lbf) and pound-foot (lb·ft) refer to the same unit size. "Foot-pound" is traditional for energy and work; "pound-foot" is often used for torque in automotive contexts, but the numerical value is identical.

How many kJ is a typical firearm muzzle energy?

A 9mm pistol produces roughly 0.5 kJ (370 ft·lbf) of muzzle energy. A .308 rifle produces about 3.6 kJ (2,650 ft·lbf). These values vary by load and barrel length.

Why are engine torque specs sometimes given in ft·lbf instead of N·m?

The US automotive industry has historically used the imperial ft·lbf for torque. Most other countries use newton-meters (N·m). 1 N·m = 0.737562 ft·lbf, so the relationship is the same as for energy — matching the J-to-ft·lbf constant.

Kilojoules to Foot Pounds Converter

Name: Kilojoules to Foot Pounds Converter
Availability: InStock
Author: Nham Vu

Enter kilojoules or foot-pounds for instant bidirectional energy conversion, with a quick-reference table for common values.

kJ ↔ ft·lbf Converter

Kilojoules (kJ)

Joules (J)

⇅

Foot-Pounds (ft·lbf)

ft·lbf

1 kJ = 737.562 ft·lbf — 1 ft·lbf = 1.35582 J

Quick Reference Table

Common kJ values in foot-pounds (1 kJ = 737.562 ft·lbf)

Kilojoules (kJ)	Joules (J)	ft·lbf

1 ft·lbf = 1.35581794833 J — international foot and pound-force definition

Common real-world references

9mm pistol muzzle energy: ~0.5 kJ (370 ft·lbf)
.308 rifle muzzle energy: ~3.6 kJ (2,650 ft·lbf)
Typical car engine torque: 200–540 N·m = 148–398 ft·lbf (0.2–0.54 kJ as magnitude)
Standard Charpy impact test: 300 J = 0.3 kJ (221 ft·lbf)
One food calorie (kcal): 4.184 kJ (3,085 ft·lbf)

Summary

Enter kilojoules or foot-pounds for instant bidirectional energy conversion, with a quick-reference table for common values.

How it works

Enter a value in the Kilojoules field to see the foot-pound (and joules) equivalent instantly.
Enter a value in the Foot-Pounds field to reverse-convert back to kilojoules and joules.
The Joules field also accepts input and converts in both directions.
All fields update in real time — no button click needed.
Click any row in the reference table to load that value into the converter.

Use cases

Convert firearm muzzle energy figures given in kJ to ft·lbf for US ballistics comparisons.
Translate engine torque or impact energy specs between metric kJ and imperial ft·lbf.
Verify bow or crossbow draw energy ratings reported in both kilojoules and foot-pounds.
Convert structural engineering impact energy values between SI and imperial unit systems.
Translate physics or mechanical engineering homework answers from kJ to ft·lbf.

Frequently Asked Questions

Last updated: 2026-07-22 · Reviewed by Nham Vu