Unit Conversion Formulas
Comprehensive reference guide for accurate unit conversion formulas across all measurement categories, sourced from international standards
📋 Formula Categories
Pressure Conversion Formulas
Pressure conversions are fundamental in engineering, meteorology, and medical applications. All formulas are based on Pascal (Pa) as the SI base unit.
Step 1: Convert PSI to Pascal: 50 × 6,894.757 = 344,737.85 Pa
Step 2: Convert Pascal to Bar: 344,737.85 ÷ 100,000 = 3.45 Bar
Pressure Unit Relationships
| From Unit | To Unit | Multiply By | Application |
|---|---|---|---|
| PSI | Bar | 0.0689476 | Automotive, industrial |
| Bar | PSI | 14.5038 | US engineering conversion |
| kPa | PSI | 0.145038 | Metric to imperial |
| mmHg | kPa | 0.133322 | Medical applications |
Temperature Conversion Formulas
Temperature conversion requires both multiplication factors and offset additions due to different zero points between scales.
🌡️ Temperature Reference Points
- Absolute Zero: 0K = -273.15°C = -459.67°F = 0°R
- Water Freezing: 273.15K = 0°C = 32°F = 491.67°R
- Water Boiling: 373.15K = 100°C = 212°F = 671.67°R
- Human Body: 310.15K = 37°C = 98.6°F = 558.27°R
Length & Distance Conversion Formulas
Length conversions between metric and imperial systems, with exact and derived relationships.
Step 1: Convert to total inches: (6 × 12) + 3 = 75 inches
Step 2: Convert to centimeters: 75 × 2.54 = 190.5 cm
Weight & Mass Conversion Formulas
Mass conversion formulas for everyday and scientific applications. Note: weight and mass are technically different but often used interchangeably.
Weight vs. Mass Distinction
⚖️ Technical Definitions
- Mass: Amount of matter (kg, g, slug)
- Weight: Force due to gravity (N, lbf)
- Earth Weight Formula: Weight = Mass × 9.80665 m/s²
- Common Usage: “Weight” often refers to mass in daily life
Volume & Capacity Conversion Formulas
Volume conversions for liquids, gases, and bulk materials across metric and imperial systems.
US gallons = 2.5 L ÷ 3.78541 = 0.660 gallons
Cooking Measurement Conversions
| Unit | Milliliters (mL) | US Equivalent | Notes |
|---|---|---|---|
| 1 teaspoon | 4.92892 | 1/3 tablespoon | Often rounded to 5 mL |
| 1 tablespoon | 14.7868 | 3 teaspoons | Often rounded to 15 mL |
| 1 cup | 236.588 | 16 tablespoons | Often rounded to 240 mL |
Speed & Velocity Conversion Formulas
Speed and velocity conversions for automotive, aviation, and scientific applications.
Physical Constants for Conversions
Fundamental physical constants used in unit conversions and scientific calculations.
🔬 Universal Constants
- Speed of light in vacuum: c = 299,792,458 m/s (exact)
- Planck constant: h = 6.62607015 × 10⁻³⁴ J⋅s (exact)
- Elementary charge: e = 1.602176634 × 10⁻¹⁹ C (exact)
- Avogadro constant: Nₐ = 6.02214076 × 10²³ mol⁻¹ (exact)
🌍 Earth & Standard Conditions
- Standard gravity: g = 9.80665 m/s² (exact)
- Standard atmosphere: 101,325 Pa (exact)
- Standard temperature: 273.15 K = 0°C (exact)
- Molar gas constant: R = 8.314462618 J/(mol⋅K) (exact)
📏 Defining Relationships
- International inch: 1 in = 2.54 cm (exact)
- International pound: 1 lb = 0.45359237 kg (exact)
- Nautical mile: 1 nmi = 1,852 m (exact)
- International calorie: 1 cal = 4.184 J (exact)
Source Standards
All conversion factors and constants are sourced from:
- NIST (National Institute of Standards and Technology) – US measurement standards
- BIPM (International Bureau of Weights and Measures) – International SI standards
- CODATA – Committee on Data for Science and Technology
- ISO (International Organization for Standardization) – International standards
Formula Usage Guidelines
🎯 Accuracy and Precision
- Exact vs. Approximate: Some conversions are exact definitions (1 in = 2.54 cm), others are measured values
- Significant Figures: Match the precision of your input data; don’t claim false precision
- Rounding: Round final answers appropriately for your application
🔄 Order of Operations
- Temperature: Always apply multiplication before addition/subtraction
- Complex Units: Convert numerator and denominator separately (e.g., m/s to ft/min)
- Chain Conversions: Use intermediate steps to avoid compounding errors
⚠️ Common Formula Mistakes
- Temperature Offset: Forgetting to add/subtract 32 or 273.15
- Imperial Variations: US vs. Imperial gallons, different ton definitions
- Unit Confusion: Mass vs. weight, volume vs. capacity
- Precision Errors: Using too few decimal places in conversion factors
❌ Wrong: 75 × 5/9 + 32 = 73.67°C
✅ Correct: (75 – 32) × 5/9 = 23.89°C
Always follow the correct order: subtract offset first, then multiply
Important Disclaimer
⚠️ Educational and Reference Use Only
Medical Information: Any formulas, conversion factors, or references related to medical measurements (blood pressure, body temperature, etc.) are provided for educational purposes only and are not intended as medical advice, diagnosis, or treatment recommendations.
Professional Medical Consultation: Never use these conversion formulas for medical decisions, diagnostic procedures, or treatment planning. Always consult qualified healthcare professionals for any medical measurements or calculations.
Critical Applications: For engineering, scientific research, medical practice, or safety-critical applications, always verify formulas and conversion factors using authoritative sources and professional-grade references. Consult with qualified professionals in your specific field.
Formula Accuracy: While all formulas are based on internationally recognized standards (NIST, BIPM, CODATA), users are responsible for verifying the appropriateness and accuracy of these formulas for their specific applications and requirements.
Limitation of Liability: ConversionCalculator.net and its contributors disclaim any liability for consequences arising from the use of these formulas or conversion factors in any application.