Convert linear current density between ampere/metre, ampere/centimetre and per-inch units.
Electricity • 5 units
All 5 units on the Linear Current Density Converter are defined against the Ampere/meter (A/m), so each result is one conversion factor away from a single reference rather than the end of a chain of roundings.
The conversion this page is most often opened for is ready before you type anything: 1 A/m = 0.01 A/cm. Change either side and every row in the table recalculates with it.
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The conversions here follow the length unit: 1 A/m is 0.01 A/cm, and 1 A/in is 39.37 A/m. What makes the quantity worth its own page is that it shares its unit, the ampere per metre, with magnetic field strength — and that is not a coincidence. At the surface of a good conductor the tangential magnetic field equals the surface current density flowing there, so the same number describes the sheet of current and the field it produces, which is the basis of how shielding and waveguide walls are analysed.
In rotating machines this quantity is a headline design parameter under the name specific electric loading: the ampere-turns per metre of stator circumference. Industrial induction motors typically run somewhere in the range of tens of kiloamperes per metre, and the figure matters because torque per unit rotor volume is set by the product of electric loading and airgap flux density. Push the electric loading up and the machine gets smaller for the same torque; push it too far and there is nowhere for the copper losses to go.
The practical trap is confusing this quantity with current per unit area. A plating or busbar specification given per unit width and one given per unit cross-section are different physical statements, and they are not interchangeable without knowing a thickness. Older process sheets compound the problem by using amperes per inch and amperes per foot alongside SI, so the safest habit is to read the denominator carefully before converting — a length and an area in that position lead to entirely different answers.
Quick reference — 1 Ampere/meter (A/m) is equal to:
| Milliampere/meter | mA/m | 1,000 |
| Ampere/centimeter | A/cm | 0.01 |
| Ampere/inch | A/in | 0.0253999992 |
| Kiloampere/meter | kA/m | 0.001 |
5 units of linear current density, each a fixed multiple of the A/m. The table spans 1,000,000:1, from mA/m (0.001 A/m) to kA/m (1000 A/m). Conversion is one multiplication into the base unit and one division out of it, with no lookup table and no approximation.
value_to = value_from × (factor_from ÷ factor_to)1 A/m = 1 A/m1 mA/m = 0.001 A/m1 A/cm = 100 A/m1 A/in = 39.3701 A/m1 kA/m = 1000 A/mwhere:
Assumptions: Factors are exact definitions. Full double precision is carried internally and rounding is applied only for display.
Result25 A/m = 0.25 A/cm
Linear current density is current per unit width, in amperes per metre (A/m), and it describes a sheet of current rather than a wire carrying one. It is the right quantity for a plated surface, a busbar face, or a current returning through a ground plane.
Electroplating is where it does the most work. Plating quality depends on current per unit area of workpiece, not on total current, so a bath running correctly for a small part will burn a large one at the same supply setting. The field also uses amperes per inch and amperes per foot in older process sheets, and mixing those with SI is a common source of finish defects.