Ohm’s Law & Power Calculator

Welcome to Store Shoppe’s Ohm’s Law & Power Calculator. This tool allows you to calculate unknown electrical parameters—Voltage, Current, Resistance, Power, and Energy—by entering any two known values.

The results update in real time, and a step-by-step calculation section shows the formulas used, helping you understand the logic behind the numbers.

This calculator is ideal for electronics enthusiasts, DIY makers, repair engineers, and students learning basic circuits. Whether you’re selecting a battery for a small device or checking component power ratings, this tool provides quick and reliable calculations.

📚 How to Use

1. Enter Your Known Values
Input your voltage in the “Voltage” field and select the unit (V / mV / kV).
Input your current in the “Current” field and select the unit (A / mA / µA).
Input your resistance in the “Resistance” field and select the unit (Ω / kΩ / MΩ).
Input your battery capacity in the “Capacity” field and select the unit (mAh / Ah).

Tip: You only need to enter any two known values. The calculator will compute all other unknown values automatically.

2. View the Results

The “Results” section shows the calculated values for Voltage, Current, Resistance, Power, and Energy (if Capacity is provided). Units are automatically adjusted for readability (e.g., kV, mA, MΩ, kW, Wh).

3. Check Calculation Steps

The “Calculation Steps” section shows the formulas and intermediate calculations used, such as R = V ÷ I or I = V ÷ R. This is useful for teaching or verifying calculations.

4. Reset the Calculator

Click the Reset button to clear all input fields and results and start over.

5. Using Battery Capacity

If you input a battery capacity (Ah or mAh) along with voltage, the calculator can compute energy (Wh).
Example: 2 Ah capacity at 12 V → energy ≈ 24 Wh.

🔍 Typical Use Cases

Battery Life Estimation: Use voltage, current, and capacity to estimate device runtime.
Circuit Maintenance: Calculate current using voltage and resistance to ensure safe operation.
Teaching & Learning: Demonstrate how changing values affects the circuit.
Electronics Design: Estimate power consumption to plan heat dissipation or component ratings.

❓ Frequently Asked Questions (FAQ)

Q1: What is Ohm’s Law?
A1: Ohm’s Law describes the relationship between Voltage (V), Current (I), and Resistance (R): V = I × R.

Q2: How do I use this calculator?
A2: Enter any two known values (Voltage, Current, Resistance, or Capacity) and select the units. The calculator will compute all remaining values, including Power and Energy if applicable.

Q3: Can it calculate Power and Energy?
A3: Yes. Power (P) is calculated as P = V × I. If Capacity (Ah) is entered along with Voltage (V), Energy (E) = V × Ah.

Q4: What units are supported?
A4: Supported units include:

Voltage: V / mV / kV
Current: A / mA / µA
Resistance: Ω / kΩ / MΩ
Capacity: mAh / Ah
Power and Energy units are automatically formatted for readability (e.g., mW, kW, Wh).

Q5: What if I enter more than two values?
A5: The calculator is designed for two primary inputs. Entering more than two may lead to conflicting results. It’s recommended to use only two known values at a time.

Q6: Can I leave Capacity blank?
A6: Yes. Without Capacity, the calculator will compute Voltage, Current, Resistance, and Power. Energy calculation requires Capacity input.

Q7: Are negative or zero values allowed?
A7: Only positive values should be entered. Zero or negative inputs can cause mathematical errors (like division by zero). Very small values are handled automatically (e.g., µA, mV).

Q8: Is this tool accurate for high-voltage or industrial applications?
A8: This tool provides basic calculations suitable for education, DIY, and small electronic projects. For industrial systems (high kV, kA, AC or complex circuits), consult professional software or engineers.

🧭 Tips & Best Practices
Ensure units match the values you input (e.g., 1 V = 1000 mV).
Enter realistic values to avoid extreme results.
To estimate runtime: Time ≈ Ah ÷ I (hours).
For teaching, demonstrate how changing Resistance affects Current and Voltage.
Copy or screenshot the “Calculation Steps” for documentation or sharing.