kilogram-force
Low (technical/archaic)Formal, Technical
Definition
Meaning
A non-SI unit of force equal to the gravitational force exerted on a mass of one kilogram.
A legacy unit of force used primarily in engineering, physics, and metrology, particularly in contexts where weight and force are equated. Its value is defined as the force a one-kilogram mass exerts under standard gravity (9.80665 m/s²). It is being largely superseded by the newton (N) in scientific contexts.
Linguistics
Semantic Notes
This is a compound noun with a hyphen. It is a defined, exact unit of measurement. In many scientific contexts, it is considered deprecated or legacy, as it conflates mass (kg) and force. It is sometimes abbreviated as 'kgf' or 'kp' (for kilopond).
Dialectal Variation
British vs American Usage
Differences
No significant difference in meaning or usage between UK and US English. Both regions are moving towards exclusive use of the newton in scientific and educational settings. The term might appear slightly more often in older British engineering documents.
Connotations
Slightly dated, technical, precise. May connote a practical, field-based (e.g., mechanical engineering) rather than a theoretical physics context.
Frequency
Extremely low in general language. Found almost exclusively in historical technical texts, certain engineering subfields, or educational materials explaining unit conversions.
Vocabulary
Collocations
Grammar
Valency Patterns
A force of [number] kilogram-forceIt measures [number] kilogram-forceConvert [number] newtons to kilogram-forceVocabulary
Synonyms
Neutral
Weak
Usage
Context Usage
Business
Virtually never used.
Academic
Used in historical or comparative contexts in physics and engineering education; modern papers use newtons.
Everyday
Never used.
Technical
Primary context; found in older machinery specifications, some national standards, and torque wrench settings (e.g., 'tighten to 5 kgf·m').
Examples
By Part of Speech
adjective
British English
- The kilogram-force unit is obsolete.
- Check the kilogram-force rating on the gauge.
American English
- The kilogram-force measurement was taken.
- It's a kilogram-force calibration tool.
Examples
By CEFR Level
- The old scale shows weight in kilogram-force.
- One kilogram-force is defined as 9.80665 newtons.
- The spring was calibrated to deliver a force of ten kilogram-force.
- While the newton is the SI derived unit for force, the deprecated kilogram-force persists in some engineering applications due to its intuitive link to mass under Earth's gravity.
- The thrust of the early rocket engine was erroneously reported in kilogram-force, leading to a conversion error in the international consortium's calculations.
Learning
Memory Aids
Mnemonic
Think of the force a one-kilogram bag of sugar exerts on your hand when you hold it. That's roughly one kilogram-force.
Conceptual Metaphor
WEIGHT IS FORCE (This unit is a literal conceptualisation of this metaphor, equating the weight of a mass to a force).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not translate as 'килограмм-сила' in modern scientific writing; use 'ньютон'. The Russian term exists but is similarly deprecated.
- Avoid directly equating 'килограмм' (mass) with 'килограмм-сила' (force) without clarifying the gravitational context.
Common Mistakes
- Writing it without a hyphen as 'kilogram force'.
- Using it in modern scientific reports where SI units are required.
- Confusing it with the unit of mass (kilogram).
- Pronouncing 'force' as /fərˈs/ instead of /fɔːrs/ or /fɔːs/.
Practice
Quiz
What is the primary reason the kilogram-force is considered deprecated in science?
FAQ
Frequently Asked Questions
No. A kilogram is a unit of mass. A kilogram-force is a unit of force, defined as the weight of a one-kilogram mass under standard gravity.
The most common symbols are 'kgf' and 'kp' (for kilopond).
In all modern scientific, technical, and educational contexts, you should use the newton (N), the SI unit of force. Use kilogram-force only when interpreting older documents or specific legacy equipment.
Multiply the value in kilogram-force by 9.80665 to get the equivalent force in newtons. For example, 1 kgf = 9.80665 N.