Newtons to Poundals: 1 N equals 7.23301 pdl. To convert newtons to poundals, multiply by 7.23301 (pdl = N × 7.23301). For example, 10 N = 72.3301 pdl.
How to Convert Newtons to Poundals
To convert from newtons to poundals, multiply the value by 7.23301. The conversion is linear, meaning doubling the input doubles the output.
Conversion Formula
- Newtons to Poundals:
pdl = N × 7.23301 - Poundals to Newtons:
N = pdl ÷ 7.23301
Newtons to Poundals Conversion Chart
| Newtons (N) | Poundals (pdl) |
|---|---|
| 0.1 | 0.723301 |
| 0.25 | 1.808253 |
| 0.5 | 3.616505 |
| 1 | 7.23301 |
| 2 | 14.46602 |
| 3 | 21.69903 |
| 5 | 36.16505 |
| 10 | 72.3301 |
| 20 | 144.6602 |
| 25 | 180.82525 |
| 50 | 361.6505 |
| 100 | 723.301 |
| 250 | 1808.2525 |
| 1000 | 7233.01 |
Understanding the Units
What is a Newton?
The newton is the SI derived unit of force, equal to the force needed to accelerate one kilogram by one meter per second squared (1 N = 1 kg·m/s²).
Named after Sir Isaac Newton (1643–1727), whose three laws of motion underpin classical mechanics.
Common contexts: mechanics, engineering.
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.
Real-World Reference Points
| Item | Newtons (N) | Poundals (pdl) |
|---|---|---|
| Weight of an apple (≈100 g) | 1 | 7.233 |
| Weight of 1 kg on Earth | 9.81 | 70.9558 |
How to Convert Newtons to Poundals
To convert newtons to poundals, multiply by 7.23301385. The factor is the SI-to-FPS reciprocal of the poundal\'s definition: one poundal is the force that accelerates 1 pound-mass at 1 ft/s². Converting through SI base units gives 0.45359237 kg × 0.3048 m/s² = 0.138254954376 N exactly, and the reciprocal of that yields 7.23301385 poundals per newton.
Conversion Formula
- Newtons to Poundals: pdl = N × 7.2330138512
- Poundals to Newtons: N = pdl × 0.138254954376
- Through pound-force: 1 lbf = 32.17404856 pdl (the dimensionless g in FPS)
The conversion is exact, not measured: all three contributing constants — the 1959 international pound, the international foot, and the metric definitions of kilogram and metre — are defined exactly. The poundal-to-newton bridge therefore inherits an exact decimal value.
Common Conversions
| Newtons (N) | Poundals (pdl) | Pound-force (lbf) |
|---|---|---|
| 0.5 | 3.6165 | 0.1124 |
| 1 | 7.2330 | 0.2248 |
| 2 | 14.4660 | 0.4496 |
| 4.4482 (1 lbf) | 32.1740 | 1.0000 |
| 5 | 36.1651 | 1.1240 |
| 9.80665 (1 kgf) | 70.9316 | 2.2046 |
| 10 | 72.3301 | 2.2481 |
| 20 | 144.6603 | 4.4962 |
| 50 | 361.6507 | 11.2404 |
| 100 | 723.3014 | 22.4809 |
| 250 | 1,808.2535 | 56.2022 |
| 500 | 3,616.5069 | 112.4045 |
| 1,000 | 7,233.0139 | 224.8089 |
| 5,000 | 36,165.0693 | 1,124.0447 |
Understanding the Units
What Is a Newton?
The newton (N) is the SI derived unit of force, defined as 1 kg·m/s². It is a "coherent" unit, meaning Newton\'s second law F = m × a holds without inserting a numerical conversion factor when all quantities are in SI base units. Adopted in 1948, the newton is the universal language of modern mechanics, engineering, and physics.
What Is a Poundal?
The poundal (pdl) is an absolute Imperial unit of force, defined as the force needed to accelerate one pound-mass (lbm) at one foot per second squared: 1 pdl = 1 lbm·ft/s² = 0.138254954376 N exactly. The poundal exists for one purpose: to make the FPS system coherent so that F = m × a works directly with pound-mass, foot, and second, with no numerical fudge factor.
Absolute vs Gravitational Force Units
This is the key conceptual point. The pound-force is gravitational: it is defined as the weight of one pound-mass at Earth\'s surface, and it carries the value of g implicitly. The poundal is absolute: it has no gravity baked in, only mass and acceleration. In any FPS calculation where you do not want g cluttering the algebra — projectile motion in vacuum, momentum, impulse, kinetic energy in pure kinematics — the poundal is the cleaner choice.
Real-World Poundal References
Because the poundal is small (1 pdl ≈ 0.14 N) and gravity-free, it suits physics-class problems more than everyday weighing. Practical anchors:
| Source of Force | Newtons (N) | Poundals (pdl) |
|---|---|---|
| Standard apple weight (≈100 g) | 0.98 | 7.09 |
| Weight of one pound-mass (1 lbm × g) | 4.448 | 32.17 |
| Force to lift a 1-kg textbook | 9.81 | 70.96 |
| Hand-thrown baseball, peak push during throw | 20–40 | 145–290 |
| Person pushing a stalled shopping trolley | 50–150 | 362–1,085 |
| Average adult bite force | ~700 | ~5,063 |
| 9 mm pistol bullet at muzzle (peak) | ~3,000 | ~21,700 |
| Rifle bullet on chamber pressure peak | ~15,000 | ~108,500 |
| Small model-rocket motor (Estes C6) | peak ~14 | ~101 |
| Compact-car braking force (full stop) | ~7,000 | ~50,600 |
Notice how the poundal scale produces large numbers for everyday forces. That is the chief practical reason it lost ground to the newton and pound-force: humans dislike four-digit force values for ordinary objects.
Poundals in Physics Education and Ballistics
British physics syllabuses through the mid-20th century treated the poundal as the standard FPS force unit precisely because it keeps F = m × a clean when masses are in pounds. Sample exam-style problem: "A 16-pound mass falls freely; what is the gravitational force on it in poundals?" Answer: F = m × g = 16 lbm × 32.174 ft/s² = 514.8 pdl. No conversion constants, no slugs, no headaches — that was the pedagogical appeal.
In external ballistics, the poundal occasionally survives in older Imperial-only references for muzzle thrust, drag force, and trajectory calculations. A bullet experiencing 3,000 pounds-force of pressure-on-base inside the barrel registers as 96,522 pdl in poundal arithmetic — large numbers, but consistent with mass-in-grains and velocity-in-feet-per-second. Modern internal-ballistics codes work in SI, but the conversion remains useful when digesting period literature.
Related Force Converters
- Poundals to Newtons — the reverse direction
- Newtons to Pounds-force — gravitational Imperial unit
- Pounds-force to Newtons — 32.174 poundals per lbf
- Newtons to Dynes — the CGS absolute force unit
- Newtons to Kilonewtons — SI step up
Brief History of the Poundal
The poundal was introduced in 1879 by Irish-Scottish engineer and physicist James Thomson — older brother of Lord Kelvin — to solve a specific irritation in Victorian engineering. Practitioners wanted to use Newton\'s second law in Imperial units without dragging the gravitational constant g through every equation. The slug, the other FPS solution, redefined mass; Thomson\'s poundal kept mass in familiar pounds and instead defined a small new force unit. The proposal was formalised at the British Association meeting in Dublin that year.
For a few decades the poundal flourished in British physics and engineering texts. But its small magnitude — about one-seventh of a newton — produced unwieldy numbers for ordinary forces, and the parallel rise of SI made it redundant in most professional contexts. By the 1960s the unit was already curatorial; today it survives mainly in physics-education exam questions and historical ballistics references where keeping mass and force units clean still appeals to teachers and antiquarians alike.