Quick reference tools
Electronics calculators
for the bench.
Resistor codes, Ohm's law, voltage dividers, LED resistors, RC circuits — everything you need, instantly. No login, no signup.
Browse all toolsFeatured Tools
View all →Resistor Color Code Decoder
Decode 4-band, 5-band, and 6-band resistors. Reverse lookup: type a value, get the color bands.
↳ 4.7 kΩ · ±5% · Brown Black Red Gold
Ohm's Law Calculator
Enter any two of V, I, R, P — get the other two instantly. Includes power triangle diagram.
↳ V = 12 V · I = 240 mA · R = 50 Ω
Voltage Divider Calculator
Live schematic, optional load resistance, power dissipation per resistor. Most tools skip the load — this one doesn't.
↳ Vin 5 V · R1 10 kΩ · R2 6.8 kΩ → Vout 2.07 V
Parallel & Series Resistor Calculator
Add up to 8 resistors in parallel or series. Shows equivalent resistance and nearest E24 standard value.
↳ 1 kΩ ∥ 1 kΩ ∥ 2.2 kΩ = 421 Ω → E24: 430 Ω
LED Resistor Calculator
Required resistor, nearest standard value, and power rating from supply voltage and LED specs. Color presets included.
↳ 5 V · Red LED (2 V, 20 mA) → 150 Ω, ¼ W
RC Time Constant Calculator
τ, charge/discharge times, and cutoff frequency from R and C. Animated charge curve updates on every keystroke.
↳ 10 kΩ · 100 nF → τ = 1 ms · fc = 159 Hz
How it works
01
Live results
Outputs recalculate on every keystroke. No submit button, no waiting.
02
Show the math
Every tool renders the formula it used. Understand the math, not just the answer.
03
Runs in your browser
All calculations are client-side. Your data never leaves your device.