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NIST Special Publication 330
Unit Conversion

Engineering Unit Converter provides deterministic conversion factors across 13 engineering dimensions including force, pressure/stress, torque, length, mass, and energy. All conversion factors are exact NIST SP811 and ISO 80000-1 certified reference values: Value_target = Value_source × (Factor_source / Factor_target).

Engineering Unit Converter

Convert between SI and imperial engineering units for force, pressure, torque, length, mass, temperature, power, and energy. All conversion constants sourced from NIST. Instant precision unit conversions for mechanical, civil, aerospace, and structural engineering workflows.

Supported Mechanical & Structural Engineering Units

Force Conversion

Newton (N), Kilonewton (kN), Pound-force (lbf), Kilogram-force (kgf), Dyne (dyn), Kip (1,000 lbf).

1 lbf = 4.448222 N

Pressure & Stress Conversion

Pascal (Pa), Megapascal (MPa), Gigapascal (GPa), Bar, Psi (lb/in²), Ksi (1,000 psi), Atmosphere (atm).

1 MPa = 145.0377 psi

Torque & Moment Conversion

Newton-meter (N·m), Pound-foot (lbf·ft), Pound-inch (lbf·in), Ounce-inch (ozf·in), Kilogram-force meter (kgf·m).

1 N·m = 8.850746 lbf·in

Length & Distance

Millimeter (mm), Centimeter (cm), Meter (m), Inch (in), Foot (ft), Yard (yd), Micrometer (µm), Thou/Mil (0.001 in).

1 in = 25.4 mm (exact)

Mass & Weight

Gram (g), Kilogram (kg), Metric Ton (t), Pound-mass (lb), Ounce (oz), Slug, Short Ton (US).

1 lb = 0.45359237 kg (exact)

Power & Energy

Watt (W), Kilowatt (kW), Horsepower (hp mechanical = 745.7 W), Joule (J), Kilojoule (kJ), BTU, Foot-pound (ft·lbf).

1 hp = 745.6999 W

Standards Verification

All conversion factors adhere strictly to NIST Special Publication 811 (Guide for the Use of the International System of Units) and ISO 80000-1:2022 (Quantities and units). Display precision supports up to 10 significant figures with zero floating-point accumulation errors.

Worked Engineering Conversion

Torque Conversion Example: Convert 120 N·m tightening torque to lbf·in.
T = 120 N·m × (1 / 0.112984829) ≈ 1,062.09 lbf·in (88.51 lbf·ft)

Frequently Asked Questions

What conversion standards does this calculator use?

All conversions follow NIST SP811 and ISO 80000-1:2022. Standard conversion constants (such as 1 inch = 25.4 mm, 1 lb = 0.45359237 kg) are exact mathematical definitions.

What engineering dimensions are supported?

13 primary dimensions: Length, Mass, Area, Volume, Force, Pressure / Stress, Torque / Moment, Power, Speed / Velocity, Angular Velocity, Temperature, Energy, and Flow Rate.

Is temperature conversion exact?

Yes. Temperature conversions apply the exact thermodynamic affine transformations: °F = °C × 9/5 + 32, K = °C + 273.15, and °R = °F + 459.67.

Can I convert between SI and Imperial structural units?

Yes. The calculator fully supports structural units including MPa ↔ psi / ksi, kN ↔ lbf / kip, and N·m ↔ lbf·in / lbf·ft.

How many significant figures are displayed?

Calculations are evaluated using IEEE 754 64-bit precision and formatted up to 10 significant digits without premature intermediate rounding.