The Lab
Calculator
Ohm's Law &
Power
Fill any two of voltage, current, resistance, and power to get the other two, plus a voltage divider and an LED series-resistor calculator.
Ohm's
law
Enter any two. V = I·R, P = V·I.
Voltage
mV
V
kV
Current
µA
mA
A
Resistance
Ω
kΩ
MΩ
Power
mW
W
kW
Voltage
divider
Vin (V)
R1
Ω
kΩ
MΩ
R2
Ω
kΩ
MΩ
Vout is taken across R2: Vout = Vin · R2 ÷ (R1 + R2).
LED
resistor
Supply (V)
LED Vf (V)
LED current (mA)
R = (Vsupply − Vf) ÷ I. Pick the next standard value at or above the result so the current stays at or below your target.