How to use: Decode resistor color bands to determine resistance value. Select Number of Bands (4-band standard or 5-band precision). Choose colors for each band reading left to right. Color code: Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Grey=8, White=9. Third band is multiplier (Brown=×10, Red=×100, Orange=×1K, etc.). Fourth band shows tolerance: Gold=±5%, Silver=±10%, Brown=±1%, Red=±2%. Results display: Resistance value with prefix (kΩ, MΩ), Tolerance percentage, Min/Max values accounting for tolerance. Essential for electronics repair, breadboard prototyping, and circuit building. Standard values: 100Ω, 220Ω, 1kΩ, 10kΩ, 100kΩ commonly used.

How to use: Calculate combined resistance for multiple resistors in circuit. Select Connection Type: Series (resistors end-to-end, current same through all, resistances add: Rtotal = R1 + R2 + R3) or Parallel (resistors side-by-side, voltage same across all, reciprocal formula: 1/Rtotal = 1/R1 + 1/R2 + 1/R3). Enter values for R1 and R2 (required), plus optional R3 and R4. Results show: Total Resistance and connection type. Series increases total resistance (3× 100Ω = 300Ω). Parallel decreases total resistance (3× 300Ω = 100Ω). Used in voltage dividers, current limiting, impedance matching, and custom resistance values. Essential electronics principle for circuit design.