Resistivity Calculator

Summary

This resistivity calculator solves for any one of the four variables in R = ρL/A: resistance (R), resistivity (ρ), length (L), or cross-sectional area (A). Pick a common material to auto-fill its resistivity at 20 °C, or enter a custom value. Results are shown in automatically scaled SI units.

How it works

1. Select which variable you want to solve for (R, ρ, L, or A).
2. Enter the known values in the remaining three fields.
3. Optionally pick a common material from the preset list to auto-fill ρ.
4. Click Calculate to get the result with the correct SI unit.
5. Use the unit dropdowns to convert inputs to non-SI units if needed.

Use cases

• Determine the resistance of a copper wire given its dimensions.
• Find the required cross-sectional area for a wire with a target resistance.
• Calculate resistivity of an unknown material from measured R, L, and A.
• Design PCB traces and cables by computing resistance from geometry.
• Physics homework and lab reports involving Ohm's law extensions.
• Compare resistivity of conductors, semiconductors, and insulators.

Frequently Asked Questions