Kilograms-force to Poundals: 1 kgf equals 70.931612 pdl. To convert kilograms-force to poundals, multiply by 70.931612 (pdl = kgf × 70.9316). For example, 10 kgf = 709.31612 pdl.
How to Convert Kilograms-force to Poundals
To convert from kilograms-force to poundals, multiply the value by 70.931612. The conversion is linear, meaning doubling the input doubles the output.
Conversion Formula
- Kilograms-force to Poundals:
pdl = kgf × 70.9316 - Poundals to Kilograms-force:
kgf = pdl ÷ 70.9316
Kilograms-force to Poundals Conversion Chart
| Kilograms-force (kgf) | Poundals (pdl) |
|---|---|
| 0.1 | 7.093161 |
| 0.25 | 17.732903 |
| 0.5 | 35.465806 |
| 1 | 70.931612 |
| 2 | 141.863224 |
| 3 | 212.794836 |
| 5 | 354.65806 |
| 10 | 709.31612 |
| 20 | 1418.63224 |
| 25 | 1773.2903 |
| 50 | 3546.5806 |
| 100 | 7093.1612 |
| 250 | 17732.903 |
| 1000 | 70931.612 |
Understanding the Units
What is a Kilograms-force?
A kilogram-force equals exactly 9.80665 newtons — the gravitational force on a one-kilogram mass at standard gravity.
Common contexts: legacy engineering, tire pressure (kgf/cm²).
What is a Poundal?
A poundal equals approximately 0.138255 newtons — the force needed to accelerate one pound-mass by one foot per second squared.
Common contexts: absolute foot-pound-second system.
How to Convert Kilograms-force to Poundals
To convert kilograms-force to poundals, multiply by 70.9316. The kilogram-force is a gravitational metric unit (the weight of a 1 kg mass under standard gravity); the poundal is an absolute imperial unit (the force needed to accelerate one pound-mass at one foot per second squared). The conversion bridges two different unit philosophies in addition to two different unit systems.
Conversion Formula
- Kilograms-force to Poundals: pdl = kgf × 70.9316
- Poundals to Kilograms-force: kgf = pdl ÷ 70.9316 ≈ pdl × 0.014098
- Scientific notation: 1 kgf ≈ 7.09316 × 10¹ pdl
The factor is exact at the rational value 70.9316482... derived from 1 kgf = 9.80665 N and 1 pdl = 0.138254954376 N. Both component definitions are themselves exact, so the bridge factor is also exact and just rounded for display.
Common Conversions
| Kilograms-force (kgf) | Poundals (pdl) | Real-world reference |
|---|---|---|
| 0.05 | 3.55 | AA battery |
| 0.15 | 10.64 | Tennis ball |
| 0.42 | 29.79 | Standard football (soccer ball) |
| 0.85 | 60.29 | Loaf of supermarket bread |
| 1.2 | 85.12 | Hardcover novel |
| 2.5 | 177.33 | Bag of flour |
| 3.7 | 262.45 | Newborn baby (lower range) |
| 5.3 | 375.94 | One-gallon jug of water |
| 8.2 | 581.64 | Bowling ball (heavy) |
| 12.5 | 886.65 | Small dog |
| 25 | 1,773.29 | Bag of cement (UK standard) |
| 68 | 4,823.35 | Average adult woman |
| 110 | 7,802.48 | Olympic clean-and-jerk record load |
| 200 | 14,186.32 | Heavy motorcycle (dry weight, lower end) |
Understanding the Units
What Is a Kilogram-force?
The kilogram-force (symbol: kgf), historically called the kilopond (kp), is the gravitational force exerted by a one-kilogram mass under standard gravity. Its exact value is 1 kgf = 9.80665 N. It is a non-SI gravitational unit retained on European industrial tooling, pressure gauges (kgf/cm²), and crane load ratings.
What Is a Poundal?
The poundal (symbol: pdl) is the imperial absolute unit of force in the foot-pound-second (FPS) system. It is defined as the force needed to accelerate a one-pound mass at one foot per second squared: 1 pdl = 1 lb·ft/s² = 0.138255 N. The unit was introduced in 1879 by British physicist James Thomson to provide a coherent imperial-system counterpart to the SI newton — a force unit that did not embed gravity into its definition.
Gravitational vs Absolute Force Units
Force units split into two camps. Gravitational units — kgf, gf, lbf, ozf, tonne-force — define force as mass times standard gravity, so a 1 kg object reads "1 kgf" on any scale on Earth. Absolute units — newton, dyne, poundal — define force purely from F = ma, without reference to gravity. The kgf-to-pdl conversion is a rare case that crosses both the metric/imperial divide and the gravitational/absolute divide in a single step.
- Metric gravitational: kgf, gf, tonne-force
- Metric absolute (SI): newton, dyne, micronewton
- Imperial gravitational: lbf, ozf, ton-force
- Imperial absolute (FPS): poundal
The FPS System in Engineering Practice
The foot-pound-second absolute system never displaced the gravitational pound-force in everyday American engineering, but it remains useful in pedagogy. Treating "pound" as a mass and "poundal" as the force unit makes Newton\'s second law come out cleanly: a 5-pound bowling ball accelerated at 1 ft/s² requires a 5-pdl push. By contrast, the gravitational system requires the slug — a unit of mass equal to 32.174 lb — to keep the equation tidy: a 1-slug mass accelerated at 1 ft/s² needs a 1-lbf push.
Older British textbooks (Sir Edmund Whittaker, Lamb\'s Dynamics) used poundals freely, and the unit appears in ballistics tables and naval gunnery handbooks from the early 20th century. Most modern American engineering practice prefers the slug-foot-second system or, increasingly, pure SI. Whenever a legacy specification quotes thrust or drag in poundals, the kgf-to-pdl conversion is the natural way to translate it into a familiar gravitational frame of reference.
Related Force Converters
- Kilograms-force to Newtons — base SI conversion
- Poundals to Newtons — absolute imperial to SI
- Kilograms-force to Pounds-force — gravitational metric to gravitational imperial
- Newtons to Poundals — SI to absolute imperial
- Pounds-force to Newtons — imperial gravitational to SI
Brief History of the Poundal
The poundal was proposed in 1879 by James Thomson (brother of Lord Kelvin) as the imperial-system counterpart to the dyne and, later, the newton — an absolute force unit free of gravitational baggage. It became the standard force unit in the foot-pound-second absolute system promoted by British physicists through the late 19th and early 20th centuries. The kilogram-force, defined by the 3rd General Conference on Weights and Measures in 1901, embodied the opposite philosophy on the metric side. The two units have therefore coexisted for over 120 years as parallel — and philosophically opposed — answers to the question of what counts as a "natural" unit of force.