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Electrical Calculators
Ohm's Law, resistors, capacitors, and more.
Ohm's Law
Fill in any two fields to solve for the others.
Voltage
Current
Resistance
Power
Resistors
Series adds values · Parallel combines reciprocals
R1
R2
Capacitors
Parallel adds values · Series combines reciprocals
C1
C2
Voltage Divider
Vout = Vin × R2 / (R1 + R2)
Vin
R1
R2
LED Resistor
R = (Vs − Vf) / If · Supply must be greater than LED forward voltage
Supply Voltage (Vs)
V
Forward Voltage (Vf)
V
Forward Current (If)
mA
RC Time Constant
τ = R × C · Time to reach 63.2% charge
Resistance (R)
Capacitance (C)
Power Cost
Power
W
Hours / Day
hr
Days
days
Rate
$/kWh