Quick answer
Stress σ = force ÷ area, where 1 MPa = 1 N/mm² = 145.04 psi. A 50,000 N force on a 400 mm² section produces 125 MPa (18,129.7 psi).
Enter the force and the cross-sectional area. The calculator returns stress in MPa and psi.
Related tools: Moment of Inertia Calculator: Area moment of inertia of common cross-sections.
How to use the Stress Calculator
- Enter force (N) (above 0).
- Enter area (mm²) (above 0).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Force | A number, in N | > 0 |
| Area | A number, in mm² | > 0 |
Formula and method
Formula
σ = F ÷ A; 1 MPa = 1 N/mm² = 145.0377 psi
IEEE-754 double precision; shown to the decimals indicated.
Applies to axial (normal) or direct shear stress.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Force = 50000; Area = 400.
| Result | Value |
|---|---|
| Stress | 125 MPa |
| In psi | 18,129.72 |
Example 2
Inputs: Force = 1200; Area = 25.
| Result | Value |
|---|---|
| Stress | 48 MPa |
| In psi | 6,961.81 |
Example 3
Inputs: Force = 800; Area = 3.2.
| Result | Value |
|---|---|
| Stress | 250 MPa |
| In psi | 36,259.43 |
The first line is the headline result (stress). Below it the stress Calculator lists in psi, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
Compare with strength
125 MPa is below the yield strength of mild steel (about 250 MPa), giving a factor of safety of 2. Aluminium alloys yield at 100 to 400 MPa, depending on the grade.
Uniform distribution assumed
The formula assumes the load is spread evenly over the section. Holes, notches and bending create stress concentrations that raise local stress. Use the area perpendicular to the force.
How the result changes with force
Holding every other input at the first worked example, this table changes only force. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Force | Stress | In psi |
|---|---|---|
| 25000 | 62.5 MPa | 9,064.86 |
| 50000 | 125 MPa | 18,129.72 |
| 100000 | 250 MPa | 36,259.43 |
| 200000 | 500 MPa | 72,518.87 |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Force: entering "0" shows "Force must be greater than 0." beside that field and no result.
- Area: entering "0" shows "Area must be greater than 0." beside that field and no result.
Choosing between the Stress Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Beam Bending Stress Calculator](/engineering/beam-bending-stress-calculator/) | bending moment, distance from neutral axis and second moment of area | Bending stress |
| [Beam Deflection Calculator](/engineering/beam-deflection-calculator/) | beam and load, load and span | Maximum deflection |
| [Moment of Inertia Calculator](/engineering/moment-of-inertia/) | section and dimension a | Moment of inertia (Ix) |
| [Column Buckling Calculator](/engineering/column-buckling-calculator/) | modulus of elasticity, smallest second moment of area and column length | Critical load |
| [Factor of Safety Calculator](/engineering/factor-of-safety-calculator/) | strength or capacity and applied load or stress | Factor of safety |
Background: structural and wiring estimates
Structural and electrical results are only as good as their assumptions. Bending stress is the bending moment divided by the section modulus, and an allowable stress is the yield strength divided by a safety factor that depends on the governing design code and the type of load. For a single-phase or DC run the voltage drop uses the round-trip length: V = 2 × L × R per unit length × I.
Recommended limits, such as keeping branch-circuit voltage drop around 3%, differ between sources and code editions. These pages are estimates: follow the applicable code and a qualified engineer or electrician for real work.
Assumptions and limitations
- Uniform stress distribution assumed
Use results as engineering estimates and check them against the governing standards, safety factors and a qualified engineer's judgement before relying on them.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for force and area to confirm this.
Frequently asked questions
What is the unit MPa?
Megapascal, 1,000,000 pascals.
How do I convert to psi?
Multiply MPa by 145.04.
Is stress the same as pressure?
They share units but stress acts within a material.
What does the Stress Calculator calculate?
Normal or shear stress from force and area. It returns Stress and In psi.
What formula does the Stress Calculator use?
σ = F ÷ A; 1 MPa = 1 N/mm² = 145.0377 psi. Applies to axial (normal) or direct shear stress.
What do I need to enter in the stress Calculator?
You enter Force (N) and Area (mm²).
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Uniform stress distribution assumed.
What is an example of a stress result?
With force 50000 and area 400, the stress is 125 MPa.
Can I rely on this calculator for a decision?
Use results as engineering estimates and check them against the governing standards, safety factors and a qualified engineer's judgement before relying on them. For this calculator in particular: Uniform stress distribution assumed.
Related calculators
- Moment of Inertia Calculator — Area moment of inertia of common cross-sections.
- Strain Calculator — Engineering strain from change in length.
Sources
- OpenStax, University Physics Volume 1 (Rice University): mechanics
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.