VOLTLAB
Everyday electricity — circuits, static, and hands-on STEM experiments.
From solving Ohm’s law and decoding a resistor’s color bands to combining series and parallel resistances, estimating battery life, sizing an LED resistor, and estimating a static charge, VoltLab pairs free hands-on electricity calculators with practical guides and a richly illustrated museum. Low-voltage, hands-on, and safe.
Electricity Tools & Calculators
Free tools for hands-on electricity — Ohm’s law calculator, resistor color code calculator, series/parallel resistance calculator, battery life calculator, LED series-resistor calculator, and a static charge demo guide.
Ohm's Law Calculator
Solve for voltage, current, resistance, or power from any two known values — the core relationship behind every DC circuit
Resistor Color Code Calculator
Decode a 4-band or 5-band resistor's color stripes into its resistance and tolerance using the standard EIA color code
Series/Parallel Resistance Calculator
Combine two or more resistors wired in series or parallel into a single total resistance
Battery Life Calculator
Estimate how many hours a battery will power a given current draw from its rated mAh capacity
LED Series-Resistor Calculator
Work out the resistor value and power rating needed to drive an LED safely from a supply voltage
Static Charge Demo Guide
Estimate the capacitance and charge of a charged sphere — the physics behind a Van de Graaff generator
Museum of Electricity
Wander an immersive museum of the people, apparatus, and discoveries behind everyday electricity — the pioneers who first described charge and current, the Van de Graaff generators that turn a crank into a spark, the Leyden jars that first bottled static electricity, and the early batteries and lightning research that connected it all — each in its own gallery, so you can get to know the story behind how we came to understand and use electricity.
Tour the museum →From the Blog
Fresh guides on Ohm’s law, resistors, batteries, LED circuits, and the science of static electricity, plus practical low-voltage safety notes.
Ohm's Law Explained: Voltage, Current, and Resistance for Beginners
A plain-language walkthrough of V = I × R — what voltage, current, and resistance actually mean, how they relate, and how to use the triangle trick to rearrange the formula on the fly.
How to Read Resistor Color Codes (4-Band and 5-Band)
The standard resistor color code decoded band by band — what each color means as a digit, multiplier, or tolerance, and how 4-band and 5-band resistors differ.
Series vs Parallel Circuits: What's Actually Different
Why resistors add up in series but combine differently in parallel, with worked examples and the intuition for why a parallel combination is always smaller than its smallest part.
Choosing the Right Resistor for an LED: A Beginner's Guide
Why an LED needs a series resistor at all, how to calculate the right value from supply voltage and forward voltage, and how to round to a real, buyable part.
AA, AAA, 9V: A Beginner's Guide to Battery Types and Capacity
What mAh capacity actually means, how common battery sizes compare, and why a battery's real-world runtime is usually less than the simple math suggests.
The Science of Static Electricity: Why Balloons Stick to Walls
The triboelectric effect explained — how rubbing two materials together transfers charge, why a charged balloon sticks to a wall, and how the same idea scales up to a Van de Graaff generator.
Keep Learning
Plain-language explainers on Ohm’s law, resistors, batteries, LED circuits, and static electricity — the foundations behind the numbers the tools produce.
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