Foot-Poundal to Joule Converter

How it is calculated

The conversion is one multiplication: joules = foot-poundals × 0.0421401100938048. The factor comes straight from the unit definitions. A poundal is the force that gives one pound of mass an acceleration of one foot per second squared, so 1 pdl = 0.45359237 kg × 0.3048 m/s² ≈ 0.138255 N. A foot-poundal is that force acting over one foot, so 1 ft·pdl = 0.138255 N × 0.3048 m ≈ 0.0421401 J.

The result is shown with six decimals and the unit J. Zero and negative values are accepted, and negatives keep their sign. Very small values are not collapsed to zero: the tool widens the decimals to keep about three significant digits, so 0.001 ft·pdl gives 0.000042 J. The second line repeats your input as ft·pdl; it is not a converted value. A decimal comma such as 12,5 is rejected and shows no result. A foot-poundal is not a foot-pound-force, which is about 32.17 times larger.

Common mistakes

• Confusing the foot-poundal with the foot-pound (ft·lbf). A foot-pound-force is about 1.3558 J, roughly 32 times more than a foot-poundal, so mixing them gives answers that are far off.
• Using this for torque in lb·ft. The two have the same dimensions but torque is not energy, and torque in foot-pounds uses pounds-force.
• Entering a decimal comma such as 12,5. The field needs a decimal point and otherwise shows no result.
• Reading the second line as a converted-back value. It only repeats your input.
• Rounding the factor to 0.04 before multiplying on large values. Use the six-decimal result instead.