Drift Velocity Calculator
Find how fast charge carriers actually drift through a conductor given the current, carrier density, cross-sectional area and carrier charge.
A
1/m³
m²
C
Average velocity of charge carriers along the conductor
- 1
Denominator n × A × q
85,000,000,000,000,000,000,000,000,000 × 0.000001 × 0 = 13,617Product of carrier density, cross-section area, and carrier charge. - 2
Drift velocity vd = I ÷ (n·A·q)
1 ÷ 13,617 = 0.000073
How does this calculator work?
Drift velocity is how fast charge carriers move through a conductor on average. Divide the current by the product of carrier density, cross-sectional area and carrier charge: vd = I / (n·A·q). With the electron charge default, typical metal drift speeds are tiny — well under a millimetre per second even at amperes of current.
Formula
How this is calculated
Drift velocity is the net average velocity at which free charge carriers (usually electrons) move through a conductor under an applied electric field. Although individual electrons move rapidly and randomly, their net drift superimposed on this motion is surprisingly slow — often fractions of a millimetre per second. The calculator divides the current I (amperes) by the product of the carrier density n (carriers per cubic metre), the cross-sectional area A (square metres) and the carrier charge q (coulombs).
The relation comes from I = n × A × q × vd, which expresses that current equals the charge per carrier times the number of carriers passing a cross-section per second. Rearranging gives vd = I / (n × A × q). By default q is set to the elementary charge, 1.602 × 10⁻¹⁹ C, appropriate for electrons; you can override it for ions or multiply-charged carriers. The tool also reports the current density J = I / A for reference.
Assumptions: a uniform conductor, a single dominant carrier type and steady-state current. All inputs must use SI units. If n, A or q is zero the denominator vanishes and drift velocity is undefined, so the calculator returns no result in that case. A negative current simply indicates the opposite drift direction; the meter shows the speed magnitude.
Frequently asked questions
Conductors contain an enormous density of free electrons (around 10²⁸ per cubic metre in copper), so even a modest current is carried by huge numbers of carriers, each needing to move only fractions of a millimetre per second.
Use the free-electron density of the material. Copper is about 8.5 × 10²⁸ per cubic metre. For semiconductors n is much smaller and depends on doping.
Yes. Set q to the ionic charge (e.g. 2 × 1.602 × 10⁻¹⁹ C for a doubly charged ion) and n to the ion number density.
Also known as
TG we-Calculate Editorial Team. (2026). Drift Velocity Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/drift-velocity-calculator
TG we-Calculate Editorial Team. "Drift Velocity Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/drift-velocity-calculator.
TG we-Calculate Editorial Team, "Drift Velocity Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/drift-velocity-calculator
@misc{wecalculate_drift_velocity_calculator, title = {Drift Velocity Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/drift-velocity-calculator}}, year = {2026}, note = {TG we-Calculate} }
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