Convert Ounce Square Inches to Pound Square Inches
Ounce Square Inch (oz·in²) to Pound Square Inch (lb·in²) unit conversion — enter any value below to get an instant result, or use the table for common values.
Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.
Result
1 oz·in² = 0.062500064 lb·in²
1 Ounce Square Inch = 0.062500064 Pound Square Inches
1 Pound Square Inch = 15.999984 Ounce Square Inches
1 oz·in² in every supported unit
Conversion chart: Ounce Square Inch to Pound Square Inches
Conversion table
| Ounce Square Inch (oz·in²) | Pound Square Inch (lb·in²) |
|---|---|
| 0.01 oz·in² | 0.00062500064 lb·in² |
| 0.1 oz·in² | 0.0062500064 lb·in² |
| 1 oz·in² | 0.062500064 lb·in² |
| 2 oz·in² | 0.12500013 lb·in² |
| 3 oz·in² | 0.18750019 lb·in² |
| 5 oz·in² | 0.31250032 lb·in² |
| 10 oz·in² | 0.62500064 lb·in² |
| 20 oz·in² | 1.2500013 lb·in² |
| 50 oz·in² | 3.1250032 lb·in² |
| 100 oz·in² | 6.2500064 lb·in² |
| 1000 oz·in² | 62.500064 lb·in² |
Ounce Square Inch (oz·in²)
Definition: A small-scale US customary moment of inertia unit, equal to the rotational inertia of a 1-ounce mass located 1 inch from the axis of rotation.
History: Combines the smaller ounce mass unit (1/16 pound) with the inch, developed for describing the rotational inertia of small, lightweight rotating parts too small to be conveniently expressed in pound square inches.
Current use: Common in small motor and instrument design — servo motors, small fans, precision actuators — where component masses are naturally measured in ounces.
Pound Square Inch (lb·in²)
Definition: A finer US customary moment of inertia unit equal to the rotational inertia of a 1-pound mass located 1 inch from the rotation axis.
History: Derived from pound square foot via the standard 144 square-inches-per-square-foot relationship, used when foot-scale units would understate the precision needed for smaller rotating parts.
Current use: Applied in the design of small mechanical components — gears, pulleys, small shafts — in US manufacturing where inch-based dimensioning is standard.
Supported Units
| Unit | Symbol | In Kilogram Square Meters |
|---|---|---|
| Kilogram Square Meter | kg·m² | 1 kg·m² |
| Kilogram Square Centimeter | kg·cm² | 0.0001 kg·m² |
| Kilogram Square Millimeter | kg·mm² | 1E-06 kg·m² |
| Gram Square Centimeter | g·cm² | 1E-07 kg·m² |
| Gram Square Millimeter | g·mm² | 1E-09 kg·m² |
| Pound Square Foot | lb·ft² | 0.04214011 kg·m² |
| Pound Square Inch | lb·in² | 0.0002926397 kg·m² |
| Ounce Square Inch | oz·in² | 1.829E-05 kg·m² |
| Slug Square Foot | slug·ft² | 1.355818 kg·m² |
About These Parameters
- Value
- The number you want to convert, expressed in the "From" unit. Accepts decimals.
- From Unit
- The moment of inertia unit your input value is currently measured in.
- To Unit
- The moment of inertia unit you want the result converted into. Use the swap button to flip From and To instantly.
How Moment of Inertia Conversion Works
The Formula
Every unit here is defined by a fixed multiplier relative to the kilogram square meter. To convert a value from one unit to another:
result = value × (factor of "From" unit ÷ factor of "To" unit)
For Ounce Square Inch → Pound Square Inch: multiply by 0.062500064. For example, 1 oz·in² × 0.062500064 = 0.062500064 lb·in².
Moment of Inertia vs. Mass: Distribution Matters
Mass tells you how much matter an object has; moment of inertia tells you how hard it is to spin that object, and the two are not simply proportional. For a point mass m at distance r from the rotation axis, moment of inertia is I = m·r² — the distance is squared, so mass located far from the axis contributes far more resistance to rotation than the same mass located close to it. This is why a solid disk and a thin ring of identical mass and radius have different moments of inertia (the ring's mass all sits at the rim, at maximum distance), and why figure skaters spin faster by pulling their arms in — reducing r reduces I, and angular momentum conservation forces angular velocity to increase.
SI vs. US Customary Engineering Units
The kilogram square meter is the SI standard used in physics and mechanical engineering worldwide. US automotive and aerospace engineers instead work in pound square foot or, when applying Newton's second law directly without conversion factors, the slug square foot — built on the slug, the US customary mass unit defined so that a 1 lbf force accelerates a 1-slug mass at exactly 1 ft/s². Smaller components — gears, motors, precision instruments — are typically specified in centimeter, millimeter, or inch-based variants to keep the numbers in a readable range for their scale.
Example
1 oz·in² equals 0.062500064 lb·in². For scale, a small automotive flywheel might have a moment of inertia around 0.5 kg·m² — about 27337.343 oz·in² — meaning it takes a torque of 0.5 N·m to give it an angular acceleration of exactly 1 radian per second squared.
Frequently Asked Questions
How many Pound Square Inches are in 1 Ounce Square Inch?
1 Ounce Square Inch (oz·in²) equals exactly 0.062500064 Pound Square Inches (lb·in²).
What's the difference between moment of inertia and mass?
Mass measures how much matter an object contains and resists linear acceleration; moment of inertia measures how that mass is distributed around a rotation axis and resists angular acceleration. Two objects with identical mass can have very different moments of inertia depending on how far their mass sits from the axis — a ring resists spinning far more than a solid disk of the same mass and radius.
Why does the US customary system use the slug?
The slug is the US customary unit of mass defined so that Newton's second law (F = ma) and its rotational analog (torque = I·α) work directly with pound-force and foot units, without extra conversion factors. Using ordinary "pounds" for both force and mass creates ambiguity, so engineering calculations that need internal consistency use the slug and slug square foot instead.
How accurate are these conversions?
Every conversion factor used here is derived from the exact, internationally recognized definitions of the underlying mass and length units (the international pound, the international foot, and the slug's definition from pound-force and standard gravity) — results are limited only by floating-point display precision, not by rounded conversion constants.