Voltage Calculator
Calculate voltage, current, resistance, and power using Ohm's Law. Perfect for electricians, DIY projects, and LED installations.
⚡Enter Known Values
💡 Quick Presets
Power Consumption
Voltage
12.00 V
Current
2.00 A
All Calculated Values
⚠️ Safety Reminder
Always turn off power before working on electrical circuits. Use proper safety equipment and follow local electrical codes.
Understanding Ohm's Law
Ohm's Law is the fundamental principle of electrical circuits, describing the relationship between voltage, current, and resistance. This calculator helps you solve for any unknown value when you know the other two.
The Ohm's Law Formulas
V = I × R (Voltage = Current × Resistance)
I = V / R (Current = Voltage ÷ Resistance)
R = V / I (Resistance = Voltage ÷ Current)
P = V × I (Power = Voltage × Current)
Understanding the Units
- Voltage (V): Measured in Volts - the electrical "pressure"
- Current (I): Measured in Amps - the flow of electrons
- Resistance (R): Measured in Ohms (Ω) - opposition to current
- Power (P): Measured in Watts - energy consumption rate
Common Applications
- LED projects: Calculate resistor values for LED circuits
- Power supplies: Size your power supply correctly
- Wire sizing: Ensure wires can handle the current
- Energy costs: Calculate power consumption for devices
Frequently Asked Questions
What is Ohm's Law?
Ohm's Law states that voltage (V) equals current (I) times resistance (R), written as V = I × R. It's the fundamental relationship in electrical circuits.
How do I calculate voltage?
Voltage = Current × Resistance (V = I × R). If you know the current in amps and resistance in ohms, multiply them to get voltage in volts.
What voltage do I need for LED strips?
Most LED strips run on 12V or 24V DC. Check your LED strip specifications. 24V strips are better for longer runs as they have less voltage drop.
How do I calculate power consumption?
Power (watts) = Voltage × Current (P = V × I). For example, a 12V device drawing 2 amps uses 24 watts of power.
About This Calculator
Free voltage calculator using Ohm's Law. Calculate voltage, current, resistance, and power for electrical circuits. Perfect for DIY projects.
Frequently Asked Questions
What is Ohm's Law?
Ohm's Law states that voltage (V) equals current (I) times resistance (R), written as V = I 脳 R.
How do I use the Voltage Calculator?
Enter your values in the input fields provided, and the calculator will automatically compute results in real-time. Start with the required fields (marked with labels), then adjust optional parameters to fine-tune your calculation. Results update instantly as you change inputs, allowing you to quickly compare different scenarios. For the most accurate results, use precise figures from official documents rather than rough estimates. If you are unsure about any input, hover over the field label for a brief explanation of what value to enter.
How accurate are the results from the Voltage Calculator?
This calculator uses standard industry formulas and up-to-date 2025 data to provide reliable estimates. Results are most accurate when you input precise, verified figures. Keep in mind that calculators provide estimates based on mathematical models — real-world outcomes may vary due to factors not captured in the inputs, such as market changes, policy updates, or individual circumstances. For high-stakes decisions, use these results as a starting point and consult with a relevant professional (financial advisor, doctor, engineer, etc.) for personalized guidance.
Can I save or share my Voltage Calculator results?
You can bookmark this page or take a screenshot of your results for future reference. To share results with others, copy the page URL — your specific inputs are not stored in the URL for privacy reasons, so the recipient will need to enter their own values. For record-keeping purposes, we recommend noting your inputs and results in a spreadsheet or document. This allows you to track changes over time and compare different scenarios side by side.
What formulas does the Voltage Calculator use?
This calculator uses industry-standard formulas that are widely accepted by professionals in this field. The specific mathematical relationships and constants are based on peer-reviewed research, government guidelines, or established industry practices. Where applicable, we reference the source methodology in the educational content below the calculator. If you need to verify a specific formula for professional or academic purposes, the calculation methodology section provides detailed breakdowns of each step.