Use Ohm’s law: R = V / I
Measure voltage across the component in volts
Measure current through the component in amperes
Divide voltage by current to get resistance in ohms
For a resistor with color bands, read the color code
For a multimeter, set it to resistance mode
Disconnect power before measuring resistance
Remove the component from the circuit if needed for an accurate reading
Check the multimeter leads and range if the reading is unstable
Use series and parallel rules for combined resistance
Series: Rtotal = R1 + R2 + R3
Parallel: 1/Rtotal = 1/R1 + 1/R2 + 1/R3