Calculate voltage, current, resistance, and power using Ohms Law and Watt's Law.
About the Ohms Law Calculator
The Ohms Law Calculator is a precision engineering calculator built for professionals, engineering students, and technical users. Applying internationally recognized engineering formulas and unit standards, it delivers reliable results instantly.
Browse our full Engineering Calculators suite including the Unit Converter, Ohm’s Law Calculator, and Speed Distance Time Calculator.
📐 Formula & Methodology
V = I × R | P = V × I | P = I²R | P = V²/R
How It Works
Enter any known values and leave the unknown field blank. The calculator solves for the missing variable using the relevant engineering formula. All results display to high precision with appropriate units.
⚙️ Unit Consistency is Critical
Always ensure your input values use consistent unit systems (SI or Imperial). Mixing units is the most common source of engineering calculation errors. Use our Unit Converter to convert values before entering them.
Engineering Applications
- Electrical engineering — circuit design, component sizing, power and voltage calculations
- Mechanical engineering — force, velocity, energy, torque, and heat transfer
- Civil engineering — structural load, material quantities, and site planning calculations
- Physics education — laboratory exercises, experiment preparation, and concept verification
- Electronics hobbyists — PCB design, component selection, and circuit troubleshooting
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⚙️ Engineering Accuracy Notes
- Verify unit consistency before entering values — SI and Imperial units must not be mixed
- Results display to 4–6 significant figures, appropriate for most engineering applications
- For critical or safety-related applications, verify results independently before use in design
- Use the Unit Converter to standardize units across different measurement systems