Tools Calculator

Electrical Calculator

Enter any two values. We'll compute the other two.

First known value

Second known value

Voltage (V):

—

Current (I):

—

Resistance (R):

—

Power (P):

—

Formulas: V = I×R, P = V×I. Derived: I = V/R, R = V/I, V = √(P×R), I = √(P/R).

Modern Resistor Calculator

Color code • Series/Parallel • Voltage divider • LED resistor • Nearest E-series

Resistor Color Code

4 / 5 / 6 band

Bands

Mode

Nearest Series

Visualization updates live

Dryer Drum RPM Calculator

Motor RPM → drum RPM. Idler pulley size doesn’t change speed.

Inputs

Units

Drum Ø

Motor Pulley Ø

Idler Ø (reference)

Motor RPM

Formula: Drum RPM = Motor RPM × (Motor Pulley Ø ÷ Drum Ø)

Results

Drum RPM

—

Belt Speed

—

at motor pulley

Drum Surface

—

≈ belt speed

Enter values to see advice.

Quick Notes

Idler Ø doesn’t affect RPM (tension only).
Typical residential drum: ~40–60 RPM.
Maintain adequate belt wrap to avoid slip.