What this calculator does
Electron drift velocity works out average speed of charge carriers moving through a current-carrying wire. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulav_d = I / (nAq), q = 1.602176634×10⁻¹⁹ C (exact)
The inputs explained
| Field | What to enter |
|---|---|
| Current (A) | A number, measured in A. Starts at 10. |
| Charge carrier density (copper ≈ 8.5×10²⁸) (/m³) | A number, measured in /m³. Starts at 8.5e+28. |
| Wire cross-section area (mm²) | A number, measured in mm². Starts at 1. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with current
Every other input is held at the calculator’s starting values while current varies. Select any row to load that scenario into the calculator.
How the answer changes with current