Poundals to Millinewtons Converter

How to Convert Poundals to Millinewtons

To convert a force measurement from poundals to millinewtons, multiply the force value by the conversion factor. Since one poundal is equal to 138.255 millinewtons, you can use this formula:

The force in millinewtons is equal to the poundals multiplied by 138.255.

How Many Millinewtons Are in a Poundal?

There are 138.255 millinewtons in one poundal.

What Is a Poundal?

The poundal (symbol: pdl) is a unit of force in the foot–pound–second (FPS) absolute system of units. It is defined as the force needed to accelerate a mass of one avoirdupois pound at a rate of one foot per second squared (1 pdl = 1 lb·ft/s²). One poundal equals approximately 0.138255 newtons. The poundal was introduced to provide an absolute (non-gravitational) unit of force in the imperial/US customary system, analogous to how the newton is the absolute unit of force in the SI system. Unlike the pound-force (which depends on the local acceleration of gravity), the poundal is defined purely in terms of mass, length, and time. The relationship between the poundal and the pound-force is governed by standard gravity: 1 lbf = 32.17405 pdl (since g = 32.17405 ft/s²). This means the poundal is a much smaller unit than the pound-force. While the poundal is rarely used in modern engineering practice (having been superseded by SI units), it appears in some physics textbooks and in historical British engineering calculations. Understanding the poundal helps clarify the distinction between absolute and gravitational units of force.

One poundal is equal to:

• 0.138255 newtons (N)
• 138.255 millinewtons (mN)
• 13,825.5 dynes (dyn)
• 0.031081 pound-force (lbf)
• 0.49710 ounce-force (ozf)
• 14.098 gram-force (gf)
• 0.014098 kilogram-force (kgf)

What Is a Millinewton?

The millinewton (symbol: mN) is a unit of force equal to one thousandth (10⁻³) of a newton. The prefix “milli” denotes a factor of 10⁻³ in the International System of Units. Millinewtons are used in precision measurement, small-scale mechanical testing, and surface science. Surface tension forces, which are responsible for phenomena like capillary action and the formation of droplets, are often measured in millinewtons per metre (mN/m). Water has a surface tension of approximately 72.8 mN/m at 20 °C. In small electric motor and actuator design, the torques and forces produced are often specified in millinewtons or millinewton-metres. The thrust produced by miniature propellers and fans for drones and small UAVs may be measured in millinewtons. In analytical chemistry, the weight of small samples placed on precision balances corresponds to forces of a few millinewtons. For reference, the weight of a single grain of rice (about 25–30 mg) is approximately 0.25–0.3 mN.

One millinewton is equal to:

• 0.001 newtons (N)
• 1,000 micronewtons (μN)
• 10⁶ nanonewtons (nN)
• 0.101972 gram-force (gf)
• 10 dynes (dyn)
• 2.2481 × 10⁻⁴ pound-force (lbf)

Understanding Force Units

Force is a fundamental physical quantity that describes an interaction capable of changing the motion of an object. According to Newton’s second law, force equals mass times acceleration (F = ma). Force is a vector quantity, meaning it has both magnitude and direction.

The wide variety of force units reflects the different measurement systems that developed historically across science and engineering. Today, the newton (SI) is the international standard, but gravitational units (kilogram-force, pound-force) and CGS/FPS units (dyne, poundal) remain in use in specific industries and regions.

Major Unit Families

• SI / Metric absolute units: The newton (N) is the SI unit of force, with standard metric prefixes (nN, μN, mN, kN, MN). These are “absolute” units defined in terms of mass, length, and time (1 N = 1 kg·m/s²).
• Gravitational metric units: The gram-force (gf) and kilogram-force (kgf) are defined using standard gravity. One kgf = 9.80665 N exactly. These units directly connect mass to weight.
• Imperial / US customary units: The pound-force (lbf) and ounce-force (ozf) are gravitational units used primarily in the United States. One lbf = 4.44822 N.
• CGS absolute unit: The dyne (dyn) is the CGS system’s force unit (1 dyn = 1 g·cm/s² = 10⁻⁵ N). It is used in some specialised fields.
• FPS absolute unit: The poundal (pdl) is the FPS system’s absolute force unit (1 pdl = 1 lb·ft/s² ≈ 0.1383 N). It is mostly of historical interest.

Force in Everyday Life

• Weight: The weight of a 1 kg object is about 9.81 N (1 kgf). A 70 kg person weighs about 687 N (154.3 lbf).
• Friction: Walking, driving, and braking all depend on friction forces. The braking force of a car can reach 10–20 kN.
• Tension: Ropes, cables, and tendons carry tension forces. Climbing ropes are rated for 8–12 kN of impact force.
• Thrust: Jet engines produce 50–500 kN of thrust, while rocket engines can produce several MN.

Converting Between Force Units

All force units measure the same physical quantity, so converting between them is simply a matter of multiplying by the appropriate conversion factor. The factor is the ratio of how many newtons one unit of the source contains divided by how many newtons one unit of the target contains.

The key conversion constants are: 1 kgf = 9.80665 N (exact), 1 lbf = 4.4482216152605 N (exact), 1 dyn = 10⁻⁵ N (exact), and 1 pdl ≈ 0.138255 N.

Tips for Force Conversions

• For SI metric conversions (nN, μN, mN, N, kN, MN), each prefix step is a factor of 1,000. So 1 kN = 1,000 N = 1,000,000 mN, etc.
• To convert between gravitational units (gf, kgf, lbf, ozf) and absolute units (N, dyn, pdl), you need the standard gravity constant g = 9.80665 m/s².
• One kilogram-force equals exactly 9.80665 newtons. This is exact by definition because g_n = 9.80665 m/s² is a defined constant.
• One pound-force = exactly 4.4482216152605 newtons (= g_n × 1 lb = 9.80665 × 0.45359237).
• There are exactly 16 ounce-force in 1 pound-force, and exactly 1,000 gram-force in 1 kilogram-force.
• The dyne is a very small force: 1 N = 100,000 dyn. The poundal is also small: 1 lbf ≈ 32.174 pdl.
• Quick mental conversion: 1 N ≈ 0.225 lbf, or 1 lbf ≈ 4.45 N. Also 1 kgf ≈ 2.205 lbf.
• Don’t confuse mass and force: “kilogram” is a unit of mass, while “kilogram-force” is a unit of force. A 1 kg object weighs 1 kgf (9.81 N) only at standard gravity.

Poundals to Millinewtons Conversion Table

The following table shows conversions from poundals to millinewtons.

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