❓ Frequently Asked Questions (FAQ)
What is a resistance calculator?
A resistance calculator is an online tool that helps you calculate electrical resistance using various methods including Ohm's Law, resistor color codes, series/parallel combinations, and conductor properties. Our calculator combines six different calculation methods into one comprehensive platform for all your electrical resistance needs.
How do I read resistor color codes?
Resistor color codes use colored bands to indicate resistance value and tolerance. For 4-band resistors: the first two bands are significant digits, the third band is the multiplier (×1, ×10, ×100, etc.), and the fourth band indicates tolerance (±1%, ±5%, ±10%, etc.). Our color code calculator makes this process instant – simply select the colors and get the resistance value immediately.
What's the difference between 4-band and 5-band resistors?
4-band resistors have two significant digits and are typically used for general applications with ±5% or ±10% tolerance. 5-band resistors have three significant digits, offering higher precision with tighter tolerances like ±1% or ±2%. 6-band resistors add a temperature coefficient band for high-precision applications. Our calculator supports all formats from 3 to 6 bands.
How do I calculate series resistance?
Series resistance is calculated by adding all resistor values together: R_total = R₁ + R₂ + R₃ + ... Simply enter your resistor values separated by commas (e.g., 100, 220, 330) into our series calculator, and it will instantly compute the total resistance.
How do I calculate parallel resistance?
Parallel resistance uses the reciprocal formula: 1/R_total = 1/R₁ + 1/R₂ + 1/R₃ + ... The total resistance is always lower than the smallest individual resistor. Our parallel calculator handles this complex formula automatically – just enter your resistor values separated by commas.
Is this resistance calculator free to use?
Yes! ResistanceCalculator.online is 100% free forever. No subscriptions, no hidden fees, no advertisements, and no sign-up required. We believe essential engineering tools should be accessible to everyone – students, hobbyists, professionals, and educators worldwide.
Can I use this on my phone or tablet?
Absolutely! Our resistance calculator is fully responsive and works perfectly on all devices including smartphones (iOS and Android), tablets, laptops, and desktop computers. The interface automatically adapts to your screen size for optimal usability.
What is Ohm's Law and how does it work?
Ohm's Law states that voltage (V) equals current (I) multiplied by resistance (R): V = I × R. This fundamental relationship governs how electricity flows through conductors. Our Ohm's Law calculator lets you enter any two values to automatically calculate the third, making circuit design and troubleshooting simple.
How accurate is the conductor resistance calculator?
Our conductor resistance calculator uses the standard formula R = ρL/A (where ρ is resistivity, L is length, and A is cross-sectional area) with accurate conductivity values for common materials like copper, aluminum, silver, and gold. It provides professional-grade accuracy suitable for engineering applications.
What units does the calculator support?
Our calculator supports multiple unit systems for international compatibility. Resistance: Ω (ohms), kΩ (kiloohms), MΩ (megaohms). Length: feet, yards, inches, miles, meters, kilometers, centimeters. Diameter: inches, feet, millimeters, centimeters, meters. The calculator automatically converts between units and displays results in the most appropriate format.
Can I calculate power dissipation for resistors?
Yes! Our Power Calculator computes power dissipation using P = V × I, P = I² × R, or P = V² / R depending on which values you have available. This is essential for selecting resistors with appropriate wattage ratings (1/4W, 1/2W, 1W, etc.) to prevent overheating and component failure.
Do I need to install any software?
No installation required! ResistanceCalculator.online is a web-based tool that runs directly in your browser. Simply visit the website and start calculating immediately. Works on Chrome, Firefox, Safari, Edge, and all modern browsers without any downloads or installations.