Resistor & Circuit Guides
Formulas, reference tables, and explanations behind the calculations Resistora runs — read the theory, then jump into the tool that applies it
Standard Resistor Values — E6 to E192 Reference Tables
Full E6, E12, E24, E48, E96, and E192 standard value tables, decade by decade — the same catalog values the E-Series Finder searches.
Voltage Divider Formula, Derivation & Worked Examples
How a two-resistor voltage divider derives from Ohm's law, with the full formula, a step-by-step derivation, and worked numeric examples.
How to Calculate Parallel Resistance
The parallel resistance formula, the product-over-sum shortcut for two resistors, and why adding branches always lowers total resistance.
Series vs Parallel Resistors — When to Use Which
The difference between series and parallel resistor networks, how voltage and current behave in each, and how to pick a topology for a given circuit.
E-Series Explained: Why 4.7 kΩ Exists and 5 kΩ Doesn't
Why standard resistors only come in specific values like 4.7 kΩ instead of round numbers, and how the E6–E192 logarithmic spacing covers every tolerance band.
Resistor Tolerance and How It Stacks in a Network
What a resistor's tolerance rating actually bounds, and how worst-case error compounds across series, parallel, and mixed networks.
How to Get a Non-Standard Resistance from Standard Parts
Practical methods for reaching a resistance no single standard part provides, by combining resistors you already stock in series, parallel, or mixed circuits.
Resistor Color Code — How to Read the Bands
How to read 4-band, 5-band, and 6-band resistor color codes, including the tolerance and temperature-coefficient bands, with quick-reference tables.