📐 Core Electrical Parameters (enter any two)

Voltage (V)

Current (I)

Resistance (R)

Power (P)

V = I × R | P = V × I

Enter any two parameters to automatically derive values and get engineering insights.

⚡ Dynamic Circuit Simulation Current Particles | Thermal Effect | LED Brightness

🔬 Engineering Simulation Tools (Dynamic Diagrams)

💡 LED Current-Limiting Resistor (5V Supply)

Recommended resistor: -- Ω , Power: -- W

* Series resistor with 5V supply, dynamic current path visualization

📉 Voltage Drop over Cable

Drop: -- V , Power loss: -- W

* Dynamic illustration of voltage difference across cable ends

🔌 Current Draw Calculator

Current draw: -- A

* Ammeter-style gauge based on power and voltage

🖨️ PCB Current Capacity (IPC-2221)

Max current: -- A

* Color indicates current density / thermal effect (IPC-2221 formula)

📘 Engineering Knowledge Base · Design Guidelines

🔹 LED Resistor (5V)

Blue/White LED Vf≈3V, Red≈2V. Resistor = (5-Vf)/If, ensure power rating.

🔹 Cable Drop Standards

NEC recommends feeder drop <3%. Copper resistivity 0.0175 Ω·mm²/m, round-trip length matters.

🔹 Current Draw Estimate

Using P=U·I, quickly evaluate battery life or power supply capacity, consider peak current.

🔹 PCB Trace Capacity

1oz copper, 1mm width ~1-2A (10°C rise), derate for inner layers.

Practical Electrical Calculation Library

Use the calculator first, then review the article library for unit checks, component sizing, voltage drop, current draw, PCB traces, and safe documentation.

Formula review

Check voltage, current, resistance, and power relationships before choosing components.

Read formula basics

Practical sizing

Review LED resistors, wire voltage drop, current draw, and PCB trace current in real design contexts.

See tool overview

Design notes

Document assumptions, units, derating, and safety checks before prototyping.

Read documentation guide

Where the homepage tools help

Solving missing voltage, current, resistance, or power values from known inputs.
Checking LED current-limiting resistors for simple 5 V circuits.
Estimating copper cable voltage drop and power loss.
Reviewing load current draw and PCB trace current capacity before prototyping.

Quick FAQ

Can I enter any two values?

Yes. Enter a valid pair among voltage, current, resistance, and power to derive linked values.

Are the advanced tools still on the homepage?

Yes. LED resistor, cable drop, current draw, and PCB trace current tools remain below the core calculator.

Is this enough for safety-critical design?

No. Use the calculator as a reference and verify final designs against standards, datasheets, tests, and qualified review.

Read the full FAQ

⚡ Electrical Engineer Toolkit