Inch-Ounce to Joule
in-oz
J
Conversion History
| Conversion | Reuse | Delete |
|---|---|---|
| No conversion history to show. | ||
Quick Reference Table (Inch-Ounce to Joule)
| Inch-Ounce (in-oz) | Joule (J) |
|---|---|
| 1 | 0.007061551814226043 |
| 10 | 0.07061551814226043 |
| 20 | 0.14123103628452086 |
| 40 | 0.28246207256904172 |
| 80 | 0.56492414513808344 |
| 100 | 0.7061551814226043 |
| 160 | 1.12984829027616688 |
About Inch-Ounce (in-oz)
The inch-ounce (in·oz) is a unit of very small torque equal to approximately 0.007062 joules — 1/16 of an inch-pound. It is used for servo motor torque ratings in model aircraft and small robotics, miniature instrument spring tensions, and the adjustment of precision optical and scientific instruments. Where inch-pounds are too coarse for the application, inch-ounces provide a finer unit without switching to SI.
A small servo motor for a model aircraft may be rated at 40–80 in·oz of torque. A clock escapement spring tension is typically a few in·oz.
About Joule (J)
The joule (J) is the SI unit of energy, defined as the work done when a force of one newton displaces an object one meter in the direction of the force. It is also the energy dissipated as heat when one ampere flows through one ohm of resistance for one second. The joule underpins all other energy units in science: calories, watt-hours, and electron volts are all defined relative to it. At human scale, one joule is a small quantity — lifting a 100 g apple by one meter requires about one joule.
Lifting a medium apple (100 g) by 1 meter requires about 1 J. A typical sneeze releases roughly 1 J of kinetic energy.
Etymology: Named after English physicist James Prescott Joule (1818–1889), who experimentally established the mechanical equivalent of heat, demonstrating that work and heat are interconvertible forms of the same quantity.
Inch-Ounce – Frequently Asked Questions
What are inch-ounces used for in hobby servos and RC models?
RC servo motors are rated by torque in inch-ounces (or oz·in) because the forces involved are tiny. A standard micro servo produces 40–60 in·oz, which is enough to deflect a model aircraft aileron. High-torque digital servos for 1/10-scale RC cars reach 200–400 in·oz. The inch-ounce scale gives hobbyists whole-number specs that are easy to compare.
Why do high-end RC servos specify torque at different voltages (4.8V vs 6V)?
Servo motors produce more torque at higher voltage because the motor windings draw more current and generate a stronger magnetic field. A servo rated at 60 in·oz at 4.8 V might deliver 75 in·oz at 6 V — a 25% boost. RC pilots choose voltage based on the tradeoff: 6 V gives snappier response and more holding torque for aerobatics, but draws more current and generates more heat, reducing servo lifespan. Competition flyers often run 7.4 V for maximum performance, accepting shorter gear life.
Why use inch-ounces instead of newton-meters for small torque values?
Inch-ounces give convenient whole numbers for very small torques where newton-meters would be awkward decimals (e.g., 50 in·oz ≈ 0.353 N·m). The RC hobby, miniature clockwork, and precision instrument industries in the US developed around imperial units, and the convention persists even as SI gains ground. Many datasheets now list both units side by side.
What torque in inch-ounces does a clock or watch mechanism require?
A mechanical wristwatch mainspring delivers roughly 2–5 in·oz of torque. Larger mantel clocks may have mainspring torques of 10–30 in·oz. Escapement adjustments are even finer, sometimes below 1 in·oz. Horologists use inch-ounces (or gram-centimeters) because these scales match the delicate forces in timekeeping mechanisms.
How does inch-ounce torque relate to servo motor performance in robotics?
A servo's inch-ounce rating tells you the maximum force it can exert at one inch from the output shaft. A 100 in·oz servo can hold 100 ounces (6.25 lb) at 1 inch, or 50 ounces at 2 inches. Robotics designers use this to size servos for joint loads — a small robotic arm lifting 1 lb at 4 inches needs at least 64 in·oz, plus a safety margin of 50% or more.
Joule – Frequently Asked Questions
Why is the joule named after James Prescott Joule and not after a more famous physicist?
Joule was the first to prove experimentally that heat and mechanical work are the same thing — he measured the temperature rise of water churned by a falling weight. That 1845 brewery-funded experiment settled a centuries-old debate and earned the SI energy unit his name in 1889, well before units were named after Einstein or Feynman.
How many joules are in a kilowatt-hour on an electricity bill?
Exactly 3,600,000 joules. A kilowatt-hour is simply 1,000 watts sustained for 3,600 seconds. Utilities chose kWh because quoting home energy use in megajoules (e.g., "your fridge used 129.6 MJ this month") would confuse most customers.
What everyday action uses about one joule of energy?
Lifting a medium apple one meter off the ground takes roughly 1 J. Clicking a computer mouse uses about 1.5 mJ (0.0015 J), a heartbeat expends ~1 J, and a single typed keystroke on a mechanical keyboard is around 10–40 mJ. A joule is a surprisingly tiny amount of energy at human scale.
What is the difference between a joule and a watt?
A joule measures total energy; a watt measures the rate of energy flow (power). One watt equals one joule per second. A 60 W lightbulb consumes 60 joules every second — leave it on for an hour and it uses 216,000 J (0.06 kWh). Think of joules as liters of water and watts as the flow rate of the tap.
How does the joule relate to the calorie?
One thermochemical calorie equals exactly 4.184 joules. The "calorie" on food labels is actually a kilocalorie (4,184 J). So a 2,000-Calorie daily diet supplies about 8.4 million joules — enough energy to lift a small car roughly 850 meters straight up, if your body were 100% efficient (it is not).