Unit Converter
Conversion Result
Quick Conversions
Learning Center
What This Converter Teaches You
This tool helps you understand how to measure material stiffness across different measurement systems. You'll learn:
- How to convert between metric (SI) and imperial units
- The relationships between pressure/stress units
- How to interpret engineering values in different formats
- Practical applications in materials science and engineering
Understanding Your Input Value
How to read your input:
- Large numbers (GPa, TPa): Used for very stiff materials like metals
- Medium numbers (MPa, ksi): Common for concrete, wood, composites
- Small numbers (kPa, psi): Used for soft materials like rubber, foam
Example interpretation: 200 GPa means the material needs 200 billion Pascals of pressure to double its length (theoretically).
Step-by-Step Conversion Process
Here's what happens when you convert:
- 1 Your input value is converted to Pascals (the base SI unit)
- 2 The tool uses precise conversion factors (no approximations)
- 3 The result is formatted with your chosen precision
- 4 You see both the result AND the conversion formula
1. 200 GPa = 200 × 1,000,000,000 Pa = 200,000,000,000 Pa
2. Divide by 6894.757 (Pa per psi)
3. Result: 29,007,547.5 psi (rounded to 4 decimals: 29,007.5475 ksi)
Common Student Mistakes
- Confusing kPa and MPa: 1 MPa = 1000 kPa (they differ by 1000×!)
- Mixing up ksi and psi: ksi means "kilo-psi" (1 ksi = 1000 psi)
- Forgetting prefixes: GPa → MPa → kPa → Pa each step is ÷1000
- Unit system confusion: Imperial (psi) vs Metric (Pa) require different thinking
Exam & Study Tips
- Memorize key conversions: 1 GPa ≈ 145,000 psi (round to 150,000 for quick estimates)
- Use the "swap" button to check your work in both directions
- Test with material examples: Try converting steel (200 GPa), aluminum (69 GPa), rubber (0.01 GPa)
- For exams: Know that 1 MPa ≈ 145 psi exactly enough for multiple choice
Visual shortcut: Think of GPa as "big building" units, MPa as "car part" units, kPa as "soft material" units.
Understanding Your Results
Is my result reasonable? Check against these benchmarks:
- Metals: 50-200 GPa (7-29 million psi)
- Plastics: 1-4 GPa (145,000-580,000 psi)
- Rubber: 0.001-0.1 GPa (145-14,500 psi)
Scientific notation help: Use when numbers get very large or small. "1.23e+6" means 1.23 × 10⁶ = 1,230,000.
What is Modulus of Elasticity?
The modulus of elasticity (also known as Young's modulus) is a measure of a material's stiffness or resistance to elastic deformation under stress.
The Formula
Young's modulus (E) is defined as the ratio of stress (σ) to strain (ε) in the elastic region of the stress-strain curve:
E = σ / ε
Where:
- E = Young's modulus (modulus of elasticity)
- σ = Stress (force per unit area)
- ε = Strain (deformation per unit length)
Why Convert Modulus of Elasticity?
Different industries and regions use different unit systems for Young's modulus:
- SI Units (Pascals) are used in most scientific and international contexts
- Imperial Units (psi, ksi) are commonly used in the United States
- CGS Units (dyne/cm²) are used in some scientific fields
Conversion between these units is essential for engineering projects that involve international collaboration or use materials with specifications in different unit systems. For instance, if you're working with different stress units, understanding their relationship to modulus of elasticity is crucial.
Common Conversion Examples
| From | To | Conversion Factor | Example |
|---|---|---|---|
| 1 GPa | psi | 145,037.7377 | 200 GPa = 29,007,547.5 psi |
| 1 MPa | ksi | 0.1450377 | 200 MPa = 29.0075 ksi |
| 1 psi | Pa | 6,894.757 | 10,000 psi = 68.9476 MPa |
| 1 dyne/cm² | Pa | 0.1 | 1,000 dyne/cm² = 100 Pa |
Units Explained
Unit Guide for Beginners
When to Use Each Unit Type
Pa, kPa, MPa, GPa SI/Metric System:
- Use in: Academic papers, international projects, scientific research
- Best for: Precise calculations, computer simulations, global collaboration
- Remember: Each step is ×1000 or ÷1000 (kilo=×1000, mega=×1,000,000)
psi, ksi, Msi Imperial/US System:
- Use in: US engineering, automotive industry, construction in North America
- Best for: Field work, legacy specifications, US manufacturing
- Remember: ksi = "kilo-psi" = 1000 psi, Msi = 1,000,000 psi
N/m², kN/mm², MN/m² Force-based Units:
- Use in: Mechanical engineering, structural analysis
- Best for: Direct force calculations, beam design
- Note: 1 Pa = 1 N/m² exactly
Real-World Examples
Bridge Design
Steel girders: ~200 GPa or 29,000,000 psi. Engineers convert between units when:
- Using international steel specifications
- Collaborating with overseas teams
- Reading foreign research papers
Medical Implants
Titanium implants: ~116 GPa or 16.8 million psi. Conversion matters for:
- Matching bone stiffness (22.5 GPa)
- International medical device standards
- Research comparison across countries
Unit Memorization Shortcuts
- GPa to psi: Multiply by 145,000 (actual: 145,037.7)
- MPa to ksi: Divide by 6.9 (actual: 6.894757)
- psi to MPa: Divide by 145 (actual: 145.0377)
Visual scale:
Plastics: 1-4 GPa (bendable)
Wood: 8-13 GPa (stiff but flexible)
Concrete: 17-31 GPa (very stiff)
Aluminum: 69 GPa (metal stiffness)
Steel: 200 GPa (super stiff)
Diamond: 1050 GPa (ultimate stiffness)
General FAQ / Knowledgebase
A: Follow these guidelines:
- Check your textbook/professor's preference
- Use SI units (Pa, GPa) for homework unless specified
- Match the units in the problem statement
- For US industry jobs: Learn psi/ksi well
- When in doubt: Use GPa for metals, MPa for other materials
A: Memorize these two conversions:
- 1 GPa ≈ 145,000 psi (remember "145" like a basketball score)
- 1 MPa ≈ 145 psi (same ratio, just smaller)
Then use the power of 10:
- 10 GPa = 1,450,000 psi
- 0.1 GPa = 14,500 psi
- 100 MPa = 14,500 psi (since 100 MPa = 0.1 GPa)
A: Different situations need different precision:
- 2 decimals: Homework, estimates, quick calculations
- 4 decimals: Engineering design, material specifications
- 6+ decimals: Scientific research, calibration, standards
For exams: Use the precision requested in the question. If unsure, 4 decimals is usually safe.
Accuracy Disclaimer & Best Practices
- Material variation: Actual Young's modulus can vary ±5% due to manufacturing
- Temperature effects: Modulus changes with temperature (not accounted for here)
- Anisotropy: Some materials are stiffer in certain directions
- For critical applications: Always consult material datasheets and engineers
Best practice: Use this tool for learning, homework, and preliminary design. For final engineering calculations, verify with authoritative sources.
Material Properties
Typical Young's Modulus values for common materials
Construction Materials
| Material | GPa | psi (×10⁶) |
|---|---|---|
| Steel (structural) | 200 | 29 |
| Concrete | 17-31 | 2.5-4.5 |
| Wood (pine, parallel to grain) | 8-13 | 1.2-1.9 |
| Brick | 10-30 | 1.5-4.4 |
Metals & Alloys
| Material | GPa | psi (×10⁶) |
|---|---|---|
| Aluminum | 69 | 10 |
| Copper | 117 | 17 |
| Titanium | 116 | 16.8 |
| Brass | 100-125 | 14.5-18 |
Biological Materials
| Material | GPa | psi (×10⁶) |
|---|---|---|
| Cortical Bone | 15-30 | 2.2-4.4 |
| Dentin (tooth) | 15-25 | 2.2-3.6 |
| Wood (oak, parallel to grain) | 11-12 | 1.6-1.7 |
Polymers & Composites
| Material | GPa | psi (×10⁶) |
|---|---|---|
| Carbon Fiber Reinforced Polymer | 70-300 | 10-43.5 |
| Nylon | 2-4 | 0.3-0.6 |
| Rubber | 0.01-0.1 | 0.0015-0.0145 |
Compare Two Materials
Comparison Result
Learning from Material Properties
What Do These Numbers Mean?
Young's modulus tells you how much a material resists stretching or compressing.
Steel is 20,000 times stiffer than rubber!
That's why bridges use steel, not rubber.
Key insights from the tables:
- Metals are generally stiff: 50-200 GPa range
- Concrete is surprisingly stiff: Similar to some metals
- Wood varies by direction: Much stiffer along the grain
- Bone is well-designed: Stiff enough for support, flexible enough for impact
Visual Understanding Suggestions
Think of stiffness like these everyday items:
Rubber (0.01 GPa)
Like a soft cookie - easy to bend and squish
Wood (10 GPa)
Like a wooden ruler - bends some but mostly stays straight
Steel (200 GPa)
Like a steel beam - barely moves under heavy weight
Practical Applications for Students
- Homework problems: Use the material buttons to quickly input common values
- Design projects: Compare materials using the comparison tool
- Lab reports: Convert your experimental data between units
- Exam preparation: Test yourself by converting steel to various units
Study strategy: Memorize 3 key materials in both GPa and psi:
- Steel: 200 GPa ≈ 29,000,000 psi
- Aluminum: 69 GPa ≈ 10,000,000 psi
- Concrete: 25 GPa ≈ 3,625,000 psi
Frequently Asked Questions
PSI (pounds per square inch) and MPa (megapascals) are both units for measuring modulus of elasticity, but they belong to different measurement systems:
- PSI is part of the imperial system, commonly used in the United States
- MPa is part of the SI (metric) system, used internationally
The conversion factor is: 1 MPa ≈ 145 psi, or 1 psi ≈ 0.006895 MPa.
Different units exist because:
- Different countries/industries traditionally used different measurement systems (metric vs imperial)
- Different scales are convenient for different materials (e.g., GPa for metals, MPa for plastics)
- Historical reasons - some units were established before international standardization
- Scientific fields developed their own conventions (e.g., CGS units in physics)
This converter helps bridge these different unit systems for modern engineering needs. For related conversions, you might also find our pressure converter and stress unit converter helpful.
The conversions are mathematically precise based on standard conversion factors:
- 1 Pa = 1 N/m² (exact)
- 1 psi = 6,894.757 Pa (exact definition)
- 1 dyne/cm² = 0.1 Pa (exact)
- 1 kgf/mm² = 9.80665 MPa (standard gravity)
For most engineering purposes, 4-6 decimal places of precision (as provided by this tool) is more than sufficient. You can adjust the precision using the decimal places selector.
Young's modulus (modulus of elasticity) and material strength are related but distinct properties:
- Young's modulus describes how stiff a material is - its resistance to elastic deformation
- Strength describes how much stress a material can withstand before failure
A material can be:
- Stiff but not strong (e.g., cast iron - high modulus but brittle)
- Strong but not stiff (e.g., rubber - can withstand stress but deforms easily)
- Both stiff and strong (e.g., high-strength steel)
Engineers consider both properties when designing structures and components.
Need More Help?
Still confused about units or conversions? Try these approaches:
For Students
- Start with the Quick Conversions buttons
- Use the Material Properties as reference points
- Set precision to 2 decimals for homework
- Use the Swap button to check your work
For Professionals
- Use 4-6 decimal places for design work
- Bookmark common conversions (GPa→psi, MPa→ksi)
- Verify critical conversions in both directions
- Use Dark Mode for extended use