Electronics Calculator

Ohm's Law & Resistor Power Sizing Calculator

Quickly size current-limiting resistors for LEDs, determine pull-up resistor power dissipation, and verify voltage drops across motor driver logic rails.

Ohm's Law Calculator (V = I · R)

Voltage (V)

Current (Amperes)

Resistance (Ohms)

Total Power

24.00 W

Calculated R

6.00 Ω

Current in mA

2000 mA

Resistor Sizing

1W+ Power Resistor

LED Current-Limiting Resistor Helper

Supply Voltage V_cc (V)

LED Forward Voltage V_f (V)

Desired LED Current (mA)

Required Resistor Value:

150.0 Ω

Nearest E24 Resistor:

150 Ω

Power Dissipated:

60.0 mW

Mathematical Formulation & Engineering Notes

V = I · R, P = V · I = I² · R = V² / R. Series LED Resistor: R = (V_supply - V_forward) / I_led.