Use Ohm’s law: R = V / I
Measure voltage in volts
Measure current in amperes
Divide voltage by current to get resistance in ohms
Use a multimeter set to resistance mode for direct measurement
For series circuits, add resistances: Rtotal = R1 + R2 + R3
For parallel circuits, use: 1 / Rtotal = 1 / R1 + 1 / R2 + 1 / R3
For a single resistor with color bands, read the color code to find its value
For a conductor, use: R = ρL / A
Use resistivity ρ, length L, and cross-sectional area A
Check units and express resistance in ohms (Ω)