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Foot-pounds to Joules Converter (ft·lb to J)

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Live Conversion • ISO 80000-5:2019 Certified
1 Foot-pound = 1.35581795 Joule
1 ft·lb = 1.355818 J • 1 J = 0.737562 ft·lb
Foot-pound to Joule: One Foot-pound is equal to 1.35581795 Joules.
Certified Authority Value
1.35581795
J
Exact: 1 J ≡ 0.7375621493 ft·lb
ft·lb
ft·lb
J
J 1.35581795
Quick Values:
Conversion Formula
To convert Foot-pound to Joule, multiply by 1.35581795
ft·lb × 1.35581795 = J

Calculation: 1 ft·lb × 1.35581795 = 1.35581795 J

Common Foot-pound to Joule Calculations

Quick-lookup reference table showing calculated equivalents for standard increments between Foot-pound (ft·lb) and Joule (J).

Tap any row to calculate
Foot-pound to Joule: Primary Direct Table (15 Steps)
Foot-pound to Joule Conversion Reference Table
Conversion & Equivalent Value Scientific Notation
0.001 ft·lb 0.00135582 J 1.356 × 10⁻³
0.01 ft·lb 0.0135582 J 1.356 × 10⁻²
0.1 ft·lb 0.135582 J 1.356 × 10⁻¹
0.5 ft·lb 0.677909 J 6.779 × 10⁻¹
1 ft·lb 1.355818 J 1.356 × 10⁰
2 ft·lb 2.711636 J 2.712 × 10⁰
5 ft·lb 6.77909 J 6.779 × 10⁰
10 ft·lb 13.558179 J 1.356 × 10¹
20 ft·lb 27.116359 J 2.712 × 10¹
25 ft·lb 33.895449 J 3.39 × 10¹
50 ft·lb 67.790897 J 6.779 × 10¹
100 ft·lb 135.581795 J 1.356 × 10²
250 ft·lb 338.954487 J 3.39 × 10²
500 ft·lb 677.908974 J 6.779 × 10²
1000 ft·lb 1355.817948 J 1.356 × 10³
Joule to Foot-pound: Reciprocal Summary
Joule to Foot-pound Conversion Reference Table
Reciprocal & Equivalent Value Scientific Notation
1 J 0.737562 ft·lb 7.376 × 10⁻¹
5 J 3.687811 ft·lb 3.688 × 10⁰
10 J 7.375621 ft·lb 7.376 × 10⁰
50 J 36.878107 ft·lb 3.688 × 10¹
100 J 73.756215 ft·lb 7.376 × 10¹

Real-World Context & Everyday Benchmarks

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To help contextualize these units in everyday life, science, and engineering, here are verified real-world reference points for Foot-pound (ft·lb) and Joule (J):

Foot-pound References:

  • Mechanical energy required to raise a one-pound weight vertically by one foot (1.356 J) 1 ft·lb
  • Kinetic energy of a standard 9mm pistol handgun bullet projectile at muzzle 350 ft·lb

Joule References:

  • Mechanical work required to lift a medium culinary apple vertically by one meter 1 J
  • Kinetic energy of a standard tennis ball dropped from waist height 1 J
  • Energy consumed by a 1-watt LED pilot lamp operating for one second 1 J
ISQ Dimension: [M L² T⁻²] Coherent SI Unit: joule (J) Chemical Engineering, Solutions & Physical Chemistry

How to Convert Foot-pound to Joule

Converting Foot-pound (ft·lb) to Joule (J) is a core calculation in Energy and Work, which quantifies the physical capacity to perform mechanical work, generate heat, or emit electromagnetic radiation. This calculation navigates the boundary between the International Metric System (SI) and British Imperial / US Customary engineering standards. In contemporary metrology, Imperial units are defined in terms of exact SI standards via international agreements—notably NIST SP 811 and the 1959 International Yard and Pound Agreement. Exactly 1 Foot-pound equals 1.355818 Joule, while 1 J equals 0.737562 ft·lb.

Direct Factor1 ft·lb = 1.355818 J
Inverse Ratio1 J = 0.737562 ft·lb
Conversion ScaleMetric SI to British Imperial / US Customary Bridge
First-Principles SI Derivation ProofNIST SP 811 / ISO 80000 Compliance

Mathematical Conversion Derivation via Coherent SI Base Unit

Under the International System of Quantities (ISQ), dimensional conversion between non-SI units is rigorously resolved by bridging through the coherent SI base unit (joule (J)) without arbitrary rounding:

Vtarget=Vsource×(ksource→SIktarget→SI)V_{\text{target}} = V_{\text{source}} \times \left( \frac{k_{\text{source} \to \text{SI}}}{k_{\text{target} \to \text{SI}}} \right)
Universal Dimensional Conversion Law (ISO 80000 / NIST SP 811)
1. Source SI Bridge (ksource):1 ft·lb = 1.355818 joule (J)
2. Target SI Bridge (ktarget):1 J = 1 joule (J)
Step-by-step substitution for Foot-pound → Joule:V(J) = V(ft·lb) × ( 1.355818 / 1 ) = V(ft·lb) × 1.355818
Mathematical FormulaValue in Joule = Value in Foot-pound × 1.35581795Direct computational formula applied for standard conversion.
Worked Example

Converting 75 ft·lb yields an exact output of 101.686346 J in Joule. Under higher industrial throughput, 2500 ft·lb translates to 3389.544871 J.

Inverse check: 1 J = 0.737562 ft·lb.

Understanding Foot-pound and Joule

Foot-pound

ft·lb
Imperial / US

A Foot-pound (ft·lb) is an imperial and US customary unit for energy and work.

Applications & Practical Context

In practical energy terms, a mechanical energy required to raise a one-pound weight vertically by one foot (1.356 J) equals 1 ft·lb, a kinetic energy of a standard 9mm pistol handgun bullet projectile at muzzle equals 350 ft·lb.

Physical Setup

An energy quantity of 1 ft·lb corresponds to 1.355818 J (performing 1.355818 joules of work or heat transfer).

Conversion to SI Unit: joule (J)
1 ft·lb = 1.355818 J

Joule

J
Coherent SI Unit

The joule (J) is the coherent SI-derived unit of energy, work, and heat, named after James Prescott Joule.

Applications & Practical Context

In practical energy terms, a mechanical work required to lift a medium culinary apple vertically by one meter equals 1 J, a kinetic energy of a standard tennis ball dropped from waist height equals 1 J, a energy consumed by a 1-watt LED pilot lamp operating for one second equals 1 J.

Physical Setup

An energy of 1 joule is the work done by a force of 1 newton acting through a displacement of 1 meter, or dissipating 1 watt of electrical power over 1 second.

Conversion to SI Unit: joule (J)
1 J = 1 N·m = 1 W·s

Domain Metrology & Engineering Applications

Governing Law & Equation

First Law of Thermodynamics (Conservation of Energy: ΔU = Q - W)

Measurement Instrumentation

Rigorously quantified in laboratory and field settings using isoperibol bomb calorimeters, optical laser pulse joulemeters, and digital revenue-grade electric energy meters.

Primary Industry Sectors

Applied across electric power utility metering, thermal energy storage design, chemical plant process enthalpies, and ballistic impact engineering under international metrology standard ISO 80000-5:2019, NIST SP 811.

Physical Orders of Magnitude & Laboratory Reference Benchmarks

Physical Phenomenon / Engineering ReferenceReference ValueConverted to Joule
Mechanical energy required to raise a one-pound weight vertically by one foot (1.356 J)1 ft·lb1.355818 J
Kinetic energy of a standard 9mm pistol handgun bullet projectile at muzzle350 ft·lb474.536282 J
Institutional Metrology & Standard Authority:

Formulas, conversion coefficients, and base definitions on this page strictly adhere to the ISO 80000-5:2019, NIST SP 811 and the BIPM SI Brochure (9th Edition). Governed by First Law of Thermodynamics (Conservation of Energy: ΔU = Q - W) under ISO 80000 dimensional vector [M L² T⁻²].

Multi-Variable Engineering Bridge Thermal Enthalpy & Continuous Power

Energy to Continuous Operating Power Bridge (Watts • Kilowatts • Megawatts • Horsepower)

Calculate required average generating or consuming power P = E / t over specified timespans, bridging energy [M L² T⁻²] with continuous power [M L² T⁻³].

P = E / t
Vector: [J] ÷ [s] → [W]
Live Calculated Bridge Equivalent:
1 ft·lb at 1 Hour Continuous Run (3,600 s) = 0.0003766 W
Equals 3.7662 × 10⁻⁷ kW • 3.766161 × 10⁻¹⁰ MW • 5.0505 × 10⁻⁷ hp
SI Power
0.0003766
W
Watts
Grid / Utility
3.7662 × 10⁻⁷
kW
Kilowatts
Power Plant
3.766161 × 10⁻¹⁰
MW
Megawatts
Mechanical Rating
5.0505 × 10⁻⁷
hp
Horsepower (Mechanical)
Metric Horsepower
5.1206 × 10⁻⁷
PS
Metric Horsepower (PS)
HVAC Thermal Rating
0.0013
BTU/h
BTU per Hour
  1. 1. Normalize Input to SI Base Unit (J):
    E = 1 ft·lb × 1.35581795 = 1.35581795 J
  2. 2. Apply Engineering Parameter (t):
    Selected condition: 1 Hour Continuous Run (3,600 s) at t = 3600 s
  3. 3. Execute Governing Physical Law in SI Units:
    P = E / t = (1.35581795 J) ÷ (3600 s) = 0.00037662 W
  4. 4. Convert to Standard Engineering Units:
    • W: 0.00037662 × 1 = 0.0003766 W (Watts) • kW: 0.00037662 × 0.001 = 3.7662 × 10⁻⁷ kW (Kilowatts) • MW: 0.00037662 × 1 × 10⁻⁶ = 3.766161 × 10⁻¹⁰ MW (Megawatts) • hp: 0.00037662 × 0.001341 = 5.0505 × 10⁻⁷ hp (Horsepower (Mechanical)) • PS: 0.00037662 × 0.00136 = 5.1206 × 10⁻⁷ PS (Metric Horsepower (PS)) • BTU/h: 0.00037662 × 3.4121 = 0.0013 BTU/h (BTU per Hour)
Explore Full Power Converter →
Engineering Substance / Operating Standard Parameter Value (s) Reference State / Condition Typical Industrial & Engineering Application
1 Second Instant Discharge 1 1.0 s Peak pulse discharge rating
1 Minute Fast Delivery (60 s) 60 60 s EV fast acceleration or battery boost
1 Hour Continuous Run (3,600 s) 3600 3,600 s (1 hour) Standard 1-hour energy delivery
8 Hours (28,800 s) 28800 28,800 s (8 hours) Single shift continuous draw
24 Hours (86,400 s) 86400 86,400 s (24 hours) Full day steady-state consumption
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Frequently Asked Questions

There are exactly 1.35581795 joules (J) in 1 foot-pound (ft·lb). To calculate larger amounts manually, simply multiply your total number of foot-pounds by the conversion multiplier of 1.35581795.

The mathematical formula to convert foot-pounds to joules is: [value] * 1.35581795 = joules. Rather than doing the math manually, you can use our high-precision online calculator to process this exact equation instantly without rounding errors.

To perform the reverse calculation from joules back to foot-pounds, you must divide your starting value by 1.35581795. Our bidirectional tool automatically computes this inverse equation the moment you type into the joule input field.

1 Foot-pound is larger than 1 Joule. Specifically, 1 Foot-pound equals exactly 1.35581795 joules, making it 1.3558 times larger (a difference of 0.13 orders of magnitude). Therefore, quantities expressed in joules require a larger numerical value to represent the same physical amount.

A typical mechanical energy required to raise a one-pound weight vertically by one foot (1.356 J) measures 1 ft·lb, which corresponds to 1.3558 J (Joule).

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