Circle
A = pi d^2 / 4
Geometry calculator
Cross-Sectional Area Calculator
Find section area for stress, flow, mass, and geometry calculations.
Calculator
Enter dimensions
Select a shape where available, choose units, and read the result as dimensions update.
Result
About this calculator
How it works
Cross-sectional area is used in stress, pressure, flow, heat-transfer, and mass calculations. Select the shape and enter the dimensions that apply.
Formulas
Formulas used
Rectangle
A = b h
Hollow circle
A = pi (Do^2 - Di^2) / 4
Worked example
Example: 25 mm round bar
For a solid circular bar with diameter 25 mm, convert to 0.025 m before solving.
Area
A = pi x 0.025^2 / 4 = 4.909e-4 m2
Area in mm2
A = 490.9 mm2
Guide
How to use this calculator
- Select the shape or section type if a shape menu is shown.
- Enter the known dimensions and choose units beside each length input.
- Read the highlighted result first, then use the supporting values for related checks.
Reference
What the results mean
Cross-sectional area
The area of the cut face perpendicular to the member, flow path, or load direction.
Equivalent diameter
The diameter of a solid circle with the same area.
Assumptions and limits
Before using the result
- Inputs are treated as ideal geometric dimensions with no tolerance, chamfer, fillet, draft, roughness, or manufacturing allowance.
- Section properties are centroidal for the listed standard shapes and do not include rotation, offsets, or parallel-axis corrections.
- Use project drawings, tolerances, material data, and applicable design standards for final engineering work.
FAQ
Cross-Sectional Area Calculator questions
Can I use different units?
Yes. Select the unit beside each input. The calculator converts dimensions internally before solving.
Are these geometry results suitable for final design?
Use the results for education, screening, drafting, and early design checks. Confirm final values against project requirements, tolerances, and applicable standards.
Why do dimensions need to use the same base units?
Geometry formulas require consistent dimensions. The calculator converts entered lengths to meters before calculating area, volume, or section properties.
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