Moment of Inertia Converter

Convert area moment of inertia units including inches to the fourth, feet to the fourth, millimeters to the fourth, centimeters to the fourth, and meters to the fourth for beams, joists, steel shapes, wood members, deflection checks, and structural estimates.

Convert Moment of Inertia

1 in⁴ = 416,231.425 mm⁴
Your moment of inertia conversion result will appear here.

Common moment of inertia conversions

Inches to the fourth to millimeters to the fourth:
1 in⁴ = 416,231.425 mm⁴

Feet to the fourth to inches to the fourth:
1 ft⁴ = 20,736 in⁴

Centimeters to the fourth to inches to the fourth:
1 cm⁴ = 0.00240251 in⁴

Meters to the fourth to inches to the fourth:
1 m⁴ = 2,402,509.61 in⁴

Where moment of inertia conversions are used

Moment of inertia conversions are useful for beams, joists, rafters, steel shapes, wood members, aluminum shapes, deflection checks, stiffness comparisons, section tables, and structural calculations.

Use this converter when switching between imperial and metric area moment of inertia units for construction and engineering references.

What your moment of inertia result means

Your result shows the entered area moment of inertia converted from the starting unit into the selected ending unit. The converter also shows common equivalent values in in⁴, ft⁴, mm⁴, cm⁴, and m⁴.

This converter changes moment of inertia units only. It does not determine whether a beam is safe. Structural design depends on span, loading, support conditions, material strength, section modulus, deflection limits, bracing, connections, and code requirements.

Moment of inertia converter tips

Frequently asked questions

What is moment of inertia in structural work?

Area moment of inertia is a geometric property used to compare how a shape resists bending and deflection.

How do I convert in⁴ to mm⁴?

Multiply inches to the fourth by 416,231.425. For example, 10 in⁴ equals about 4,162,314.25 mm⁴.

What units are used for moment of inertia?

Area moment of inertia uses length to the fourth power units, such as in⁴, ft⁴, mm⁴, cm⁴, or m⁴.

Is moment of inertia the same as section modulus?

No. Moment of inertia is measured in length to the fourth power. Section modulus is moment of inertia divided by the distance to the extreme fiber.

Does this converter calculate beam deflection?

No. This converter only changes moment of inertia units and gives an optional section modulus reference when a distance is entered.